perf/x86/intel: Only check GP counters for PEBS constraints validation

perf/x86/intel: Only check GP counters for PEBS constraints validation

It's good enough to only check GP counters for PEBS constraints
validation since constraints overlap can only happen on GP counters.

Besides opportunistically refine the code style and use pr_warn() to
replace pr_info() as the message itself is a warning message.

Signed-off-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260228053320.140406-1-dapeng1.mi@linux.intel.com