ARM: 5960/1: ARM: perf-events: fix v7 event selection mask

The event selection mask for ARMv7 cores [ARMV7_EVTSEL_MASK]
is incorrectly set to 0x7f. This means that the top bit of an
event ID is ignored, so counting branch misses (id=0x10) and
ISBs (id=0x90) give the same results.

This patch sets the event selection mask to the correct value
of 0xff.

Signed-off-by: Jean Pihet <jpihet@mvista.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>