mt76: mt7921: Fix the error handling path of mt7921_pci_probe()

In case of error, some resources must be freed, as already done above and
below the devm_kmemdup() and __mt7921e_mcu_drv_pmctrl() calls added in the
commit in Fixes:.

Fixes: 602cc0c9 ("mt76: mt7921e: fix possible probe failure after reboot")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Felix Fietkau <nbd@nbd.name>