MIPS: Alchemy: au1100fb: use clk framework

Use the clock framework to en/disable the clock to the au1100
framebuffer device.

Signed-off-by: Manuel Lauss <manuel.lauss@gmail.com>
Cc: Linux-MIPS <linux-mips@linux-mips.org>
Patchwork: https://patchwork.linux-mips.org/patch/7474/


Signed-off-by: Ralf Baechle <ralf@linux-mips.org>