Checking in I2C3 (SMB) support for AXM5500

Signed-off-by: SangeethaRao <sangeetha.rao@lsi.com>
Handle the baudrate environment variable correctly and allow
the baudrate to be changed.

The default is defined by CONFIG_BAUDRATE in include/configs/axxia-arm.h
for ARM systems and include/configs/axxia-ppc.h for PowerPC systems.

The default will be used until the environment gets read in by U-Boot.

Signed-off-by: John Jacques <john.jacques@lsi.com>