efi_loader: parameter checks in StartImage and Exit()

Add parameter checks in the StartImage() and Exit() boottime services:
- check that the image handle is valid and has the loaded image protocol
  installed
- in StartImage() record the current image
- in Exit() check that the image is the current image

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
1 file changed