pinctrl: mvebu: Fix compiler warnings

match->data is const void * where as dev.platform_data is just void *.
Add a cast to remove the const, which is causing the compiler warning:

drivers/pinctrl/mvebu/pinctrl-kirkwood.c:461:26: warning: assignment
discards 'const' qualifier from pointer target type

Dove has the exact same warning, so gets the same cast.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Acked-by: Jason Cooper <jason@lakedaemon.net>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>