powerpc/fsl_uli1575: Simplify uli_exclude_device() usage

Function uli_exclude_device() is called only from mpc86xx_exclude_device()
and mpc85xx_exclude_device() functions. Both those functions are same, so
merge its logic directly into the uli_exclude_device() function.

Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230409000812.18904-4-pali@kernel.org