omap: Do not use smaller ARM_L1_CACHE_SHIFT than hardware has

Remove the part changing ARM_L1_CACHE_SHIFT from the previous
patch. Changing ARM_L1_CACHE_SHIFT is unnecessary and unsafe
as pointed out by Russell King.

Note that we also seem to have a related problem in plat-omap/iommu.c
where real cache line size should be used instead of L1_CACHE_BYTES.

Signed-off-by: Tony Lindgren <tony@atomide.com>