MIPS: Alchemy: get rid of common/reset.c

Implement reset / poweroff in the board code instead.  The peripheral reset
code is gone too since YAMON which all in-tree boards use does the same
work when it boots.

Signed-off-by: Manuel Lauss <manuel.lauss@gmail.com>
Signed-off-by: Yoichi Yuasa <yuasa@linux-mips.org>
Cc: Linux-MIPS <linux-mips@linux-mips.org>
Patchwork: http://patchwork.linux-mips.org/patch/783/
Patchwork: http://patchwork.linux-mips.org/patch/882/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>