OMAP clock: compress clock flags down to a u8

OMAP clock: compress clock flags down to a u8

There are now only eight OMAP clock flags, so renumber the flags to
fit in a u8 and shrink the size of struct clk.flags from a u32 to a
u8.  The intention is to save memory.

Signed-off-by: Paul Walmsley <paul@pwsan.com>