mpc83xx: don't shift pre-shifted ACR, SPCR, SCCR bitfield masks in cpu_init.c

commit c7190f02 "mpc83xx:
retain POR values of non-configured ACR, SPCR, SCCR, and LCRR
bitfields" incorrectly shifted <register>_<bitfield> (e.g.
ACR_PIPE_DEP) values that were preshifted by their
definition in mpc83xx.h.

this patch removes the unnecessary shifting for the newly
utilized mask values in cpu_init.c, and prevents seemingly
unrelated symptoms such as an mpc8379erdb board from
locking up whilst performing a networking operation,
e.g. a tftp.

Signed-off-by: Kim Phillips <kim.phillips@freescale.com>