msm: Perf: Differentiate between L1 and L2 PMU IRQs

The L2 perf code shares some resource reservation functions
with the L1 perf code. In these functions, use defaults
only if they're not defined for the L1 and L2.

Change-Id: I5a390aa0085694466800db78b51837556aa12cdd
Signed-off-by: Ashwin Chaugule <ashwinc@codeaurora.org>