ARM: 6049/1: ARM: pxa: register PMU IRQs during board initialisation

This patch adds an initcall for the pxa platforms so that they
register their PMU IRQs with the PMU framework in the Kernel.

Cc: Eric Miao <eric.y.miao@gmail.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>