ARM: DRA7: Add detection of ES2.0

Add support for detection of ES2.0 version of DRA7 family of
processors. ES2.0 is an incremental revision with various fixes
including the following:
- reset logic fixes
- few assymetric aging logic fixes
- MMC clock rate fixes
- Ethernet speed fixes
- edma fixes for mcasp

[ravibabu@ti.com: posted internal for an older bootloader]
Signed-off-by: Ravi Babu <ravibabu@ti.com>
Signed-off-by: Nishanth Menon <nm@ti.com>
Acked-by: Lokesh Vutla <lokeshvutla@ti.com>
Reviewed-by: Tom Rini <trini@konsulko.com>