Nokia RX-51: Update my email address

I'm using a new email address, so reflect this state also in U-Boot.

Signed-off-by: Pali Rohár <pali@kernel.org>
diff --git a/board/nokia/rx51/MAINTAINERS b/board/nokia/rx51/MAINTAINERS
index 8bdddc1..4cf3dcc 100644
--- a/board/nokia/rx51/MAINTAINERS
+++ b/board/nokia/rx51/MAINTAINERS
@@ -1,5 +1,5 @@
 RX51 BOARD
-M:	Pali Rohár <pali.rohar@gmail.com>
+M:	Pali Rohár <pali@kernel.org>
 S:	Maintained
 F:	board/nokia/rx51/
 F:	include/configs/nokia_rx51.h