uboot-imx

efi_loader: do not add \ in efi_fs_from_name()

In the `efidebug boot add` command we do not want an unsolicited leading
backslash added to the file name.

There is no good reason to mark a loaded file with a backslash as absolute.
Anyway when reading files the file name will be interpreted as relative to
root directory of the device.

So let's get rid of this backslash.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>