RISC-V: include cpufeature.h in cpufeature.c

Automation complains:
warning: symbol '__pcpu_scope_misaligned_access_speed' was not declared. Should it be static?

cpufeature.c doesn't actually include the header of the same name, as it
had not previously used anything from it.
The per-cpu variable is declared there, so include it to silence the
complaints.

Fixes: 62a31d6e ("RISC-V: hwprobe: Support probing of misaligned access performance")
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Evan Green <evan@rivosinc.com>
Link: https://lore.kernel.org/r/20230420-wound-gizzard-2b2b589d9bea@spud
Cc: stable@vger.kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

arch/riscv/kernel/cpufeature.c

@@ -14,6 +14,7 @@
 #include <linux/of.h>
 #include <asm/alternative.h>
 #include <asm/cacheflush.h>
+#include <asm/cpufeature.h>
 #include <asm/hwcap.h>
 #include <asm/patch.h>
 #include <asm/processor.h>