OMAP: hwmod: Move pr_debug to improve the readability

Move the pr_debug at the top of the function
to trace the entry even if the first test is failing.
That help understanding that we entered the function
but failed in it.

Move the _enable last part out of the test to reduce
indentation and improve readability.

Signed-off-by: Benoit Cousson <b-cousson@ti.com>
Cc: Paul Walmsley <paul@pwsan.com>
Signed-off-by: Paul Walmsley <paul@pwsan.com>