uboot-imx

MIPS: do not build position-independent executables for SPL

SPL binaries are usually linked to a fixed address in SRAM.
Furthermore SPL binaries do not need to relocate itself. Thus
do not build them as position-independent binaries which helps
to largely reduce the size of SPL binaries.

Signed-off-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>