OMAP2+: id: remove OMAP_REVBITS_* macros

The OMAP_REVBITS_* macros are just used as otherwise meaningless
aliases for the numbers zero through five, so remove these macros.

Signed-off-by: Paul Walmsley <paul@pwsan.com>
Tested-by: Igor Grinberg <grinberg@compulab.co.il>
Tested-by: Abhilash Koyamangalath <abhilash.kv@ti.com>