arm: mach-k3: common: Clean up ATF image startup function

Perform some cosmetic cleanup of the ATF image startup function, namely
fixing a spelling mistake, capitalization of a few words, spacing, as
well aligning how errors are printed and as using panic() for cases that
were using a combination of printf() + hang().

Signed-off-by: Andreas Dannenberg <dannenberg@ti.com>
Reviewed-by: Lokesh Vutla <lokeshvutla@ti.com>