perf, x86: rename macro in ARCH_PERFMON_EVENTSEL_ENABLE

For consistency reasons this patch renames
ARCH_PERFMON_EVENTSEL0_ENABLE to ARCH_PERFMON_EVENTSEL_ENABLE.

The following is performed:

 $ sed -i -e s/ARCH_PERFMON_EVENTSEL0_ENABLE/ARCH_PERFMON_EVENTSEL_ENABLE/g \
   arch/x86/include/asm/perf_event.h arch/x86/kernel/cpu/perf_event.c \
   arch/x86/kernel/cpu/perf_event_p6.c \
   arch/x86/kernel/cpu/perfctr-watchdog.c \
   arch/x86/oprofile/op_model_amd.c arch/x86/oprofile/op_model_ppro.c

Signed-off-by: Robert Richter <robert.richter@amd.com>