uboot-phytec

cmd_bdinfo: replace print_str() with print_mhz()

The print_str() helper function for cmd_bdinfo can print any string, but it
is only used to print MHz values.  Replace it with print_mhz() that takes
a number and converts it to a string internally.

Signed-off-by: Timur Tabi <timur@freescale.com>