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: 7224d5cc ("pinctrl: Add support for Kendryte K210 FPIOA")
Signed-off-by: Niklas Cassel <niklas.cassel@wdc.com>
Reviewed-by: Sean Anderson <seanga2@gmail.com>