pinctrl: single: make two arrays static const, reduces object code size

Don't populate the read-only arrays prop2 and prop4 on the stack, instead
make them static const.  Makes the object code smaller by over 230 bytes:

Before:
   text	   data	    bss	    dec	    hex	filename
  28235	   5820	    192	  34247	   85c7	drivers/pinctrl/pinctrl-single.o

After:
   text	   data	    bss	    dec	    hex	filename
  27839	   5980	    192	  34011	   84db	drivers/pinctrl/pinctrl-single.o
Signed-off-by: NColin Ian King <colin.king@canonical.com>
Acked-by: NTony Lindgren <tony@atomide.com>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/pinctrl-single.c

@@ -873,13 +873,13 @@ static int pcs_parse_pinconf(struct pcs_device *pcs, struct device_node *np,
 	int i = 0, nconfs = 0;
 	unsigned long *settings = NULL, *s = NULL;
 	struct pcs_conf_vals *conf = NULL;
-	struct pcs_conf_type prop2[] = {
+	static const struct pcs_conf_type prop2[] = {
 		{ "pinctrl-single,drive-strength", PIN_CONFIG_DRIVE_STRENGTH, },
 		{ "pinctrl-single,slew-rate", PIN_CONFIG_SLEW_RATE, },
 		{ "pinctrl-single,input-schmitt", PIN_CONFIG_INPUT_SCHMITT, },
 		{ "pinctrl-single,low-power-mode", PIN_CONFIG_LOW_POWER_MODE, },
 	};
-	struct pcs_conf_type prop4[] = {
+	static const struct pcs_conf_type prop4[] = {
 		{ "pinctrl-single,bias-pullup", PIN_CONFIG_BIAS_PULL_UP, },
 		{ "pinctrl-single,bias-pulldown", PIN_CONFIG_BIAS_PULL_DOWN, },
 		{ "pinctrl-single,input-schmitt-enable",