drm/panel: ili9322: Make local symbols static

Fixes the following sparse warnings:

drivers/gpu/drm/panel/panel-ilitek-ili9322.c:182:12: warning:
 symbol 'ili9322_inputs' was not declared. Should it be static?
drivers/gpu/drm/panel/panel-ilitek-ili9322.c:343:28: warning:
 symbol 'ili9322_regmap_config' was not declared. Should it be static?

Also change ili9322_inputs to 'const char * const' to avoid
chackpatch warning.
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1514948938-19996-1-git-send-email-weiyongjun1@huawei.com

drivers/gpu/drm/panel/panel-ilitek-ili9322.c

@@ -179,7 +179,7 @@ enum ili9322_input {
 	ILI9322_INPUT_UNKNOWN = 0xc,
 };
 
-const char *ili9322_inputs[] = {
+static const char * const ili9322_inputs[] = {
 	"8 bit serial RGB through",
 	"8 bit serial RGB aligned",
 	"8 bit serial RGB dummy 320x240",
@@ -340,7 +340,7 @@ static bool ili9322_writeable_reg(struct device *dev, unsigned int reg)
 	return true;
 }
 
-const struct regmap_config ili9322_regmap_config = {
+static const struct regmap_config ili9322_regmap_config = {
 	.reg_bits = 8,
 	.val_bits = 8,
 	.max_register = 0x44,