perf/x86/intel: Constify the 'lbr_desc[]' array and make a function static

A few minor clean-ups: constify the lbr_desc[] array and make
local function lbr_from_signext_quirk_rd() static to fix a sparse warning:

  "symbol 'lbr_from_signext_quirk_rd' was not declared. Should it be static?"
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kernel-janitors@vger.kernel.org
Link: http://lkml.kernel.org/r/20170629091406.9870-1-colin.king@canonical.comSigned-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/events/intel/lbr.c

@@ -18,7 +18,7 @@ enum {
 	LBR_FORMAT_MAX_KNOWN    = LBR_FORMAT_TIME,
 };
 
-static enum {
+static const enum {
 	LBR_EIP_FLAGS		= 1,
 	LBR_TSX			= 2,
 } lbr_desc[LBR_FORMAT_MAX_KNOWN + 1] = {
@@ -287,7 +287,7 @@ inline u64 lbr_from_signext_quirk_wr(u64 val)
 /*
  * If quirk is needed, ensure sign extension is 61 bits:
  */
-u64 lbr_from_signext_quirk_rd(u64 val)
+static u64 lbr_from_signext_quirk_rd(u64 val)
 {
 	if (static_branch_unlikely(&lbr_from_quirk_key)) {
 		/*