bootmeth: pass size to efi_binary_run()

If we call efi_binary_run() with size parameter set to zero, we get an error

     Not a PE-COFF file

Fill the missing value.

Fixes: 1373ffde ("Merge tag 'v2024.01-rc5' into next")
Fixes: 7017fc54 ("bootmeth: use efi_loader interfaces instead of bootefi command")
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>