sh: Fix up HAVE_PERF_COUNTERS typo.

That's HAVE_PERF_COUNTERS not HAVE_PERF_COUNTER. This was right
initially but I seem to have screwed it up while re-typing it out
by hand on another machine when I checked it in. Hmph.
Reported-by: Robert P. J. Day <rpjday@crashcourse.ca>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

arch/sh/Kconfig

@@ -15,7 +15,7 @@ config SUPERH
 	select HAVE_IOREMAP_PROT if MMU
 	select HAVE_ARCH_TRACEHOOK
 	select HAVE_DMA_API_DEBUG
-	select HAVE_PERF_COUNTER
+	select HAVE_PERF_COUNTERS
 	select RTC_LIB
 	select GENERIC_ATOMIC64
 	help