AArch32: Add tf_printf support

AArch32: Add tf_printf support

The tf_printf library uses 64 bit division to print numbers
in appropriate formats but AArch32 mode cannot do 64 bit division
natively. Hence this patch adds additional number printing routines
to handle AArch32 mode in tf_printf library. The decimal format
printing capability is limited to 32 bit integers whereas 64 bits
are supported in hexadecimal format. The library assumes that
secure world is running in Little-Endian mode to do bit
manipulations on 64 bit. Suitable assertions are present to
enforce this assumption.

Change-Id: I55a21e448cef4915d1834d76e48a84ccf0bec36d