uboot-phytec

efi_loader: disk: install FILE_SYSTEM_PROTOCOL only if available

In the current implementation, EFI_SIMPLEFILE_SYSTEM_PROTOCOL is always
installed to all the partitions even if some of them may house no file
system.

With this patch, that protocol will be installed only if any file system
exists.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Reviewed-by: Heinrich Schuchardt <xypron.glpk@gmx.de>