perf/amd/uncore: Fix sysfs type mismatch

dev_attr_show() calls the __uncore_*_show() functions via an indirect
call but their type does not currently match the type of the show()
member in 'struct device_attribute', resulting in a Control Flow
Integrity violation.

$ cat /sys/devices/amd_l3/format/umask
config:8-15

$ dmesg | grep "CFI failure"
[ 1258.174653] CFI failure (target: __uncore_umask_show...):

Update the type in the DEFINE_UNCORE_FORMAT_ATTR macro to match
'struct device_attribute' so that there is no more CFI violation.

Fixes: 06f2c245

 ("perf/amd/uncore: Prepare to scale for more attributes that vary per family")
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20210415001112.3024673-2-nathan@kernel.org