mach-imx: bootaux: print stack pointer and reset vector

1. Change information printed about loaded M4 binary, print the stack
pointer and reset vector addressed.
2. Add sanity check for the address provided as param.

Signed-off-by: Igor Opaniuk <igor.opaniuk@toradex.com>
Reviewed-by: Oleksandr Suvorov <oleksandr.suvorov@toradex.com>