Masked out PMXEVTYPER.NSH means that we can't enable profiling at PL2,
regardless of the settings in the HDCR.

This patch fixes the broken mask.

Cc: <stable@vger.kernel.org>
Reported-by: Christoffer Dall <cdall@cs.columbia.edu>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>