perf/x86/amd: Remove the repeated declaration

The function 'amd_brs_disable_all' is declared twice in

    commit ada54345 ("perf/x86/amd: Add AMD Fam19h Branch Sampling support").

Remove one of them.

Signed-off-by: Shaokun Zhang <zhangshaokun@hisilicon.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20221108104117.46642-1-zhangshaokun@hisilicon.com