ARM: omap: clean redundant PISMO_xx macros used in OMAP3

PISMO_xx macros were used to define 'Platform Independent Storage MOdule'
related GPMC configurations. This patch
- Replaces these OMAP3 specific macros with generic CONFIG_xx macros as provided
  by current u-boot infrastructure.
- Removes unused redundant macros, which are no longer required after
  merging of common platform code in following commit
      commit a0a37183
      ARM: omap: merge GPMC initialization code for all platform

+-----------------+-----------------------------------------------------------+
| Macro           | Reason for removal                                        |
+-----------------+-----------------------------------------------------------+
| PISMO1_NOR_BASE | duplicate of CONFIG_SYS_FLASH_BASE                        |
+-----------------+-----------------------------------------------------------+
| PISMO1_NAND_BASE| duplicate of CONFIG_SYS_NAND_BASE                         |
+-----------------+-----------------------------------------------------------+
| PISMO1_ONEN_BASE| duplicate of CONFIG_SYS_ONENAND_BASE                      |
+-----------------+-----------------------------------------------------------+
| PISMO1_NAND_SIZE| GPMC accesses NAND device via I/O mapped registers so     |
|                 | configuring GPMC chip-select for smallest allowable       |
|                 | segment (GPMC_SIZE_16M) is enough.                        |
+-----------------+-----------------------------------------------------------+
| PISMO1_ONEN_SIZE| OneNAND uses a fixed GPMC chip-select address-space of    |
|                 | 128MB (GPMC_SIZE_128M)                                    |
+-----------------+-----------------------------------------------------------+
+-----------------+-----------------------------------------------------------+
| PISMO1_NOR      |  Unused Macros                                            |
| PISMO1_NAND     |                                                           |
| PISMO2_CS0      |                                                           |
| PISMO2_CS1      |                                                           |
| PISMO1_ONENAND  |                                                           |
| PISMO2_NAND_CS0 |                                                           |
| PISMO2_NAND_CS1 |                                                           |
| PISMO1_NOR_BASE |                                                           |
| PISMO1_NAND_BASE|                                                           |
| PISMO2_CS0_BASE |                                                           |
+-----------------+-----------------------------------------------------------+

Signed-off-by: Pekon Gupta <pekon@ti.com>