bcma: fix incorrect update of BCMA_CORE_PCI_MDIO_DATA

An earlier commit re-worked the setting of the bitmask and is now
assigning v with some bit flags rather than bitwise or-ing them
into v, consequently the earlier bit-settings of v are being lost.
Fix this by replacing an assignment with the bitwise or instead.

Addresses-Coverity: ("Unused value")
Fixes: 2be25cac8402 ("bcma: add constants for PCI and use them")
Signed-off-by: Colin Ian King <[e-mail]>
Signed-off-by: Kalle Valo <[e-mail]>

drivers/bcma/driver_pci.c

···
 		v |= (address << BCMA_CORE_PCI_MDIODATA_REGADDR_SHF_OLD);
 	}
 
-	v = BCMA_CORE_PCI_MDIODATA_START;
+	v |= BCMA_CORE_PCI_MDIODATA_START;
 	v |= BCMA_CORE_PCI_MDIODATA_READ;
 	v |= BCMA_CORE_PCI_MDIODATA_TA;
 
···
 		v |= (address << BCMA_CORE_PCI_MDIODATA_REGADDR_SHF_OLD);
 	}
 
-	v = BCMA_CORE_PCI_MDIODATA_START;
+	v |= BCMA_CORE_PCI_MDIODATA_START;
 	v |= BCMA_CORE_PCI_MDIODATA_WRITE;
 	v |= BCMA_CORE_PCI_MDIODATA_TA;
 	v |= data;