powerpc/85xx: mpc85xx_ds: Simplify mpc85xx_exclude_device() function

Function mpc85xx_exclude_device() is installed and used only when
pci_with_uli is fsl_pci_primary. So replace check for pci_with_uli by
fsl_pci_primary in mpc85xx_exclude_device() and move pci_with_uli variable
declaration into function mpc85xx_ds_uli_init() where it is used.

Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230409000812.18904-3-pali@kernel.org