efi_selftest: use efi_st_error for all error messages

All error messages in the selftests should use efi_st_error.
efi_st_error will print the file name and line number of the error.

Splitting message texts due to lines being over 80
characters is avoided. This resolves the issue reported
by Simon Glass in
https://lists.denx.de/pipermail/u-boot/2017-September/307387.html



Reported-by: Simon Glass <sjg@chromium.org>
Fixes: 623b3a57 efi_selftest: provide an EFI selftest application
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Alexander Graf <agraf@suse.de>