hw/ppc: Pass error_fatal to load_image_targphys()

hw/ppc: Pass error_fatal to load_image_targphys()

Pass error_fatal to load_image_targphys() calls in ppc machine initialization
to capture detailed error information when loading firmware, kernel,
and initrd images.

Passing error_fatal automatically reports detailed error messages and
exits immediately on failure. Eliminating redundant exit(1) calls, as
error_fatal handles termination

The behavior remains functionally identical, but error messages now
come directly from the loader function with more context about the
failure cause.

Reviewed-by: Aditya Gupta <adityag@linux.ibm.com>
Reviewed-by: BALATON Zoltan <balaton@eik.bme.hu>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Vishal Chourasia <vishalc@linux.ibm.com>
Message-ID: <20251024130556.1942835-14-vishalc@linux.ibm.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>