MAINTAINERS: add rockchip regexp to the ARM/Rockchip entry

The regexp option is a nice way to catch even weirder paths like the current
drivers/gpu/drm/rockchip/* or others in the future.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>

MAINTAINERS

@@ -1351,6 +1351,7 @@ F:	drivers/i2c/busses/i2c-rk3x.c
 F:	drivers/*/*rockchip*
 F:	drivers/*/*/*rockchip*
 F:	sound/soc/rockchip/
+N:	rockchip
 
 ARM/SAMSUNG EXYNOS ARM ARCHITECTURES
 M:	Kukjin Kim <kgene@kernel.org>