ASoC: bolero: Synchronize bolero register macro function

Bolero_register_macro can be called simultaneously by different
macros as bootup resulting in inconsistent value of
num_macros_registered. This will result in one of macro going ahead and
registering bolero component and other macro failing to register which
will cause probe of other macro to fail. Protect function with mutex lock
so that macros access it sequentially.

Change-Id: Idd0110d8b0bcfdcbf9f03c293c4cdba82e0a8827
Signed-off-by: Vatsal Bucha <vbucha@codeaurora.org>