ARM: perf: make name of arm_pmu_type consistent

Commit f12482c9

 ("ARM: 6974/1: pmu: refactor reservation") changed
{release,reserve}_pmu to take an enum arm_pmu_type as a parameter, but
inconsistently named the parameter `type' or `device'. It would be nice
if these were consistent.

This patch makes use of enum arm_pmu_type consistent, always using
`type'. Related printks are updated, explicitly mentioning `type' also.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>