mmc: dw_mmc-k3: make array hs_timing_cfg static

The array hs_timing_cfg is local to the source and does not need to
be in global scope, so make it static.

Cleans up sparse warning:
symbol 'hs_timing_cfg' was not declared. Should it be static?
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/dw_mmc-k3.c

@@ -75,7 +75,7 @@ struct hs_timing {
 	u32 smpl_phase_min;
 };
 
-struct hs_timing hs_timing_cfg[TIMING_MODE][TIMING_CFG_NUM] = {
+static struct hs_timing hs_timing_cfg[TIMING_MODE][TIMING_CFG_NUM] = {
 	{ /* reserved */ },
 	{ /* SD */
 		{7, 0, 15, 15,},  /* 0: LEGACY 400k */