OMAP3 clock: add wait for USIM module to become active

This patch adds the register definitions and clock tree fields required
to wait for the USIM module to come out of idle when the USIM clocks are
enabled.  Register bit definitions are from the 34xx HS Addendum Rev B.
There, the clock is in fact named "USIM_ICLK".

Signed-off-by: Paul Walmsley <paul@pwsan.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>