efi_loader: remove asm/setjmp.h from efi_api.h

In the commit c982874e ("efi_loader: refactor
efi_setup_loaded_image()"), setjmp-related definitions were moved to
efi_loaded_image_obj in efi_loader.h. So setjmp.h is no longer
refererenced in efi_api.h.

This also fixes some error when efi_api.h will be included in
mkeficapsule.c.

Fixes: c982874e ("efi_loader: refactor efi_setup_loaded_image()")
Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Reviewed-by: Heinrich Schuchardt <xypron.glpk@gmx.de>