msm: clock: Migrate to clkdev

Migrating to clkdev has several advantages:

 * Less code in mach-msm/clock.c

 * A more robust clk_get() implementation

 * clk_add_alias() support

 * clk_get_sys() support

In general, this will help board authors setup clock aliases and
break the dependency on device pointers in the clock tables.

Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: David Brown <davidb@codeaurora.org>