pinctrl: k210: Fix loop in k210_pc_get_drive()

The loop exited too early so the k210_pc_drive_strength[0] array element
was never used.

Original Linux patch by Dan Carpenter:
https://lore.kernel.org/linux-gpio/20220209180804.GA18385@kili/

Fixes: 7224d5ccf8e1 ("pinctrl: Add support for Kendryte K210 FPIOA")
Signed-off-by: Niklas Cassel <niklas.cassel@wdc.com>
Reviewed-by: Sean Anderson <seanga2@gmail.com>
diff --git a/drivers/pinctrl/pinctrl-k210.c b/drivers/pinctrl/pinctrl-k210.c
index 63084ae..f809149 100644
--- a/drivers/pinctrl/pinctrl-k210.c
+++ b/drivers/pinctrl/pinctrl-k210.c
@@ -511,7 +511,7 @@
 {
 	int i;
 
-	for (i = K210_PC_DRIVE_MAX; i; i--)
+	for (i = K210_PC_DRIVE_MAX; i >= 0; i--)
 		if (k210_pc_drive_strength[i] < max_strength_ua)
 			return i;