cmd, nand: add more info to "nand info"

add subpagesize, nand options and bbt options to the
"nand info" output.

=> nand info

Device 0: nand0, sector size 256 KiB
  Page size       4096 b
  OOB size         256 b
  Erase size    262144 b
  subpagesize     4096 b
  options     0x     200
  bbt options 0x    8000

Signed-off-by: Heiko Schocher <hs@denx.de>