MAINTAINERS: update email address for Yixun Lan

Switch my email address to kernel.org account for more convenience.
Also add entries to the mailmap.

Signed-off-by: Yixun Lan <dlan@kernel.org>
Link: https://lore.kernel.org/r/20260115-11-maintainer-dlan-v1-1-64bb698da846@kernel.org
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Author: Yixun Lan

.mailmap

@@ -876,6 +876,8 @@ Wolfram Sang <wsa@kernel.org> <wsa@the-dreams.de>
 Yakir Yang <kuankuan.y@gmail.com> <ykk@rock-chips.com>
 Yanteng Si <si.yanteng@linux.dev> <siyanteng@loongson.cn>
 Ying Huang <huang.ying.caritas@gmail.com> <ying.huang@intel.com>
+Yixun Lan <dlan@kernel.org> <dlan@gentoo.org>
+Yixun Lan <dlan@kernel.org> <yixun.lan@amlogic.com>
 Yosry Ahmed <yosry.ahmed@linux.dev> <yosryahmed@google.com>
 Yu-Chun Lin <eleanor.lin@realtek.com> <eleanor15x@gmail.com>
 Yusuke Goda <goda.yusuke@renesas.com>

MAINTAINERS

@@ -22526,7 +22526,7 @@ F:	drivers/mailbox/riscv-sbi-mpxy-mbox.c
 F:	include/linux/mailbox/riscv-rpmi-message.h
 
 RISC-V SPACEMIT SoC Support
-M:	Yixun Lan <dlan@gentoo.org>
+M:	Yixun Lan <dlan@kernel.org>
 L:	linux-riscv@lists.infradead.org
 L:	spacemit@lists.linux.dev
 S:	Maintained