imx: bootaux fix elf loading

This reverts the arch/arm/mach-imx/imx_bootaux.c changes of commit
805b3cac. The loader function name was changed so that it does
not clash with the generically available function in lib/elf.c.

imx-bootaux loads an elf file linked for an auxilary core. Thus the
loader function requires address translation from the auxilary core's
address space to where those are mapped into U-Boot's address space.

So the elf loader is specific and must not be replaced with a generic
loader which doesn't provide the address translation functionality.

Fixes commit 805b3cac ("lib: elf: Move the generic elf
loading/validating functions to lib")

Signed-off-by: Max Krummenacher <max.krummenacher@toradex.com>
Acked-by: Oleksandr Suvorov <oleksandr.suvorov@toradex.com>