net: ipa: kill ipa_clock_get()

The only remaining user of the ipa_clock_{get,put}() interface is
ipa_isr_thread().  Replace calls to ipa_clock_get() there calling
pm_runtime_get_sync() instead.  And call pm_runtime_put() there
rather than ipa_clock_put().  Warn if we ever get an error.

With that, we can get rid of ipa_clock_get() and ipa_clock_put().

Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>