MIPS: csrc-sb1250: Remove FSF mail address from GPL notice

MIPS: csrc-sb1250: Remove FSF mail address from GPL notice

This is to make checkpatch.pl happy for the next patch. It would otherwise
say --

ERROR: Do not include the paragraph about writing to the Free Software
Foundation's mailing address from the sample GPL notice. The FSF has
changed addresses in the past, and may do so again. Linux already includes
a copy of the GPL.

Signed-off-by: Deng-Cheng Zhu <dengcheng.zhu@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: macro@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9487/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>