PPC: Add print_bats() to lib_ppc/bat_rw.c

PPC: Add print_bats() to lib_ppc/bat_rw.c

This function prints the values of all the BAT register
pairs - I needed this for debug earlier this week; adding it to
lib_ppc so others can use it (and add it to reginfo commands
if so desired).

Signed-off-by: Becky Bruce <becky.bruce@freescale.com>