staging: r8188eu: efuse_OneByteRead is unused

Remove the efuse_OneByteRead function, which is no longer used.
Remove resulting dead code as well.

Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Link: https://lore.kernel.org/r/20211113185518.23941-12-martin@kaiser.cx


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>