drm/rockchip: Fix a typo

Fix a typo in comments.

Reported-by: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Kreimer <algonell@gmail.com>
Acked-by: Andy Yan<andyshrk@163.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20240915123943.105118-1-algonell@gmail.com

drivers/gpu/drm/rockchip/cdn-dp-reg.h

@@ -77,7 +77,7 @@
 #define SOURCE_PIF_PKT_ALLOC_WR_EN	0x30830
 #define SOURCE_PIF_SW_RESET		0x30834
 
-/* bellow registers need access by mailbox */
+/* below registers need access by mailbox */
 /* source car addr */
 #define SOURCE_HDTX_CAR			0x0900
 #define SOURCE_DPTX_CAR			0x0904