OMAP3: clock: use std _MASK suffix for CM_FCLKEN_IVA2 defines

Add _MASK suffix to CM_FCLKEN_IVA2 bitfieds to conform with the rest
of the usage in cm-regbits-34xx.h of using _SHIFT and _MASK suffixes.

Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>
Signed-off-by: Paul Walmsley <paul@pwsan.com>