MAINTAINERS: pinctrl: Add git tree to Samsung pinctrl entry

Add a Git tree on @kernel.org for maintaining the Samsung pinctrl
drivers. The tree will be maintained in a shared model between current
Samsung pinctrl maintainers. Pull requests will be going to Linus
Walleij.

Also add the patchwork for linux-samsung-soc mailing list which will be
used for handling the patches.

Signed-off-by: Krzysztof Kozlowski <[e-mail]>
Acked-by: Tomasz Figa <[e-mail]>
Acked-by: Sylwester Nawrocki <[e-mail]>
Signed-off-by: Linus Walleij <[e-mail]>

MAINTAINERS

···
 M:	Sylwester Nawrocki <[e-mail]>
 L:	[e-mail] (moderated for non-subscribers)
 L:	[e-mail] (moderated for non-subscribers)
+Q:	https://patchwork.kernel.org/project/linux-samsung-soc/list/
+T:	git git://git.kernel.org/pub/scm/linux/kernel/git/pinctrl/samsung.git
 S:	Maintained
 F:	drivers/pinctrl/samsung/
 F:	include/dt-bindings/pinctrl/samsung.h