net: ipa: kill ipa_interrupt_process_all()

Now that ipa_isr_thread() is a simple wrapper that gets a clock
reference around ipa_interrupt_process_all(), get rid of the
called function and just open-code it in ipa_isr_thread().

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