Fix unconditional FatalF
Fix unconditional FatalF

We don't want to fatalf unconditionally for kexec. Only do so if we
actually get an error

Signed-off-by: Gan Shun Lim <2e7f5e6c120ad45644b6c32fd10bafcf8f554f9f@gmail.com>

rminnich/u-root,u-root/u-root,hugelgupf/u-root,u-root/u-root,rminnich/u-root,rminnich/u-root,hugelgupf/u-root,rminnich/u-root,u-root/u-root,hugelgupf/u-root,GanShun/u-root,GanShun/u-root,GanShun/u-root,hugelgupf/u-root