Coldfire: M5271EVB: Board header update (dependencies)

Cleanup for M5271EVB:
Added clarification on the use of CONFIG_SYS_CLOCK.
Modified to use u-boot's HUSH parser.
Cleanup on environment settings.
Removed compiler warning by defining CONFIG_SYS_CS0_*

Dependencies:
Added the use of CONFIG_SYS_MCF_SYNCR for clock multiplier.
This depends on a patch to include/asm-m68k/m5271.h
that defines the multiplier and divider ratios.

Removed the definition of CONFIG_SYS_FECI2C.
This depends on a patch that removes the use of it in
cpu/mcf52x2/cpu_init.c

Signed-off-by: Richard Retanubun <RichardRetanubun@RuggedCom.com>