ARM: Perf: Change event filters depending on profiling mode

The L2CC PMU is shared between all CPU's. In system wide profiling
mode, perf allocates each event for each CPU. This restricts
the number of L2 events that the user can specify.

Instead, change the event filters, such that in system wide mode
we count each event from all CPU's. This way, the user can specify
upto 4 events (which is the current limit in h/w) in system wide
profiling mode.

Task wide profiling mode is unchanged, since we need to filter
according to the CPU on which the task/thread is running.

Change-Id: Ia51fe97cdc19617f8a3cdd53409cb5f94ff2d9b3
Signed-off-by: Ashwin Chaugule <ashwinc@codeaurora.org>