omap3: Fix OMAP35XX_REV macros

In original implementation, the revision passed to
these macros contained revision number in lower nibble.

But, later the revision bits (OMAP_REVBITS_XX) were
defined to use omap_revision[15:08] where revision
number is containied in higher nibble.

This patch updates the macros; else incorrect revision
is detected for OMAP35xx devices.

Signed-off-by: Sanjeev Premi <premi@ti.com>