efi_loader: Improve the parameter check for QueryVariableInfo()

Improve efi_query_variable_info() to check the parameter settings and
return correct error code according to the UEFI Specification 2.9,
and the Self Certification Test (SCT) II Case Specification, June
2017, chapter 4.1.4 QueryVariableInfo().

Reported-by: Kazuhiko Sakamoto <sakamoto.kazuhiko@socionext.com>
Signed-off-by: Masami Hiramatsu <masami.hiramatsu@linaro.org>
Reviewed-by: Heinrich Schuchardt <xypron.glpk@gmx.de>