This mechanism makes it much easier to define and read new attributes
so move it to the arm_pmu.h header so that it can be shared. At the same
time update the existing format attributes to use it.

GENMASK has to be changed to GENMASK_ULL because the config fields are
64 bits even on arm32 where this will also be used now.
Signed-off-by: James Clark <james.clark@arm.com>
Link: https://lore.kernel.org/r/20231211161331.1277825-7-james.clark@arm.comSigned-off-by: Will Deacon <will@kernel.org>