mxcmmc.c

This patch modifies mxcmmc.c to be used
not only by i.MX27 but also by i.MX31 boards.
Both use the same SD controller, but have different
clock set-ups.
The i.MX27 imx_get_XXXclock functions are made static to
generic.c and a public mxc_get_clock() function
is provided.  Pins, base address and prototypes for
an i.MX31 specific board_init_mmc() are provided.
Some of the i.MX27 clock getters are unused and marked
as such to avoid warnings (./MAKEALL -s mx27), but
the code was left in for future use.

Signed-off-by: Helmut Raiger <helmut.raiger@hale.at>
Acked-by: Stefano Babic <sbabic@denx.de>