net: wan: Add checks for NULL for utdm in undo_uhdlc_init and unmap_si_regs

net: wan: Add checks for NULL for utdm in undo_uhdlc_init and unmap_si_regs

If uhdlc_priv_tsa != 1 then utdm is not initialized.
And if ret != NULL then goto undo_uhdlc_init, where
utdm is dereferenced. Same if dev == NULL.

Found by Astra Linux on behalf of Linux Verification Center
(linuxtesting.org) with SVACE.

Fixes: 8d68100ab4ad ("soc/fsl/qe: fix err handling of ucc_of_parse_tdm")
Signed-off-by: Esina Ekaterina <eesina@astralinux.ru>
Link: https://lore.kernel.org/r/20230112074703.13558-1-eesina@astralinux.ru
Signed-off-by: Jakub Kicinski <kuba@kernel.org>