arm: mach-k3: add support for detecting TIFSSTUB images

Add support for detecting and processing TIFSSTUB images for HS, HSFS
and GP devices.

TIFSSTUB image for related device type will be loaded, rest TIFSSTUB
images will be discarded.

Example, for GP device, tifsstub-gp will be loaded, tifsstub-hs and
tifsstub-fs will be discarded.

Signed-off-by: Kamlesh Gurudasani <kamlesh@ti.com>
Signed-off-by: Dhruva Gole <d-gole@ti.com>
Reviewed-by: Neha Malcom Francis <n-francis@ti.com>