Get rid of bogus CONFIG_SYS_BUS_HZ and CONFIG_SYS_CONFIG_BUS_CLK definitions

Get rid of bogus CONFIG_SYS_BUS_HZ and CONFIG_SYS_CONFIG_BUS_CLK definitions

CONFIG_SYS_BUS_HZ has not really been used anywhere except to be
redined as CONFIG_SYS_BUS_CLK; in addition, the mpc7448hpc2 had the
bogus CONFIG_SYS_CONFIG_BUS_CLK setting which duplicated the
funtionality.  Change all this to use CONFIG_SYS_BUS_CLK consistently.

Signed-off-by: Wolfgang Denk <[email protected]>
Cc: Frank Gottschling <[email protected]>
Cc: Reinhard Arlt <[email protected]>
Cc: Eran Man <[email protected]>
Cc: Stefan Roese <[email protected]>
Cc: Nye Liu <[email protected]>
Cc: Roy Zang <[email protected]>