efi_loader: Sort header file ordering

Order header files according to https://www.denx.de/wiki/U-Boot/CodingStyle



Suggested-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Reviewed-by: Heinrich Schuchardt <xypron.glpk@gmx.de>