PCI: brcmstb: Make two changes in MDIO register fields

The hardware has been updated with two changes to the MDIO packet
format.

The CMD field used to be 12 bits and now is only 1 bit. This change
is backwards compatible because the field's starting bit position is
unchanged, and the only commands we've used have values 0 and 1.

The PORT field's width has been changed from 4 bits to 5 bits. When
written, the new bit is not contiguous with the other four. However,
this change is backwards compatible because the driver never used
anything other than 0 for the port field's value.

Thus, update the existing code to handle new changes to the hardware
in a backwards-compatible manner.

Signed-off-by: Jim Quinlan <james.quinlan@broadcom.com>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/20250214173944.47506-8-james.quinlan@broadcom.com
[kwilczynski: commit log]
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>

Author: jamesequinlan

drivers/pci/controller/pcie-brcmstb.c

@@ -175,8 +175,9 @@
 #define MDIO_PORT0			0x0
 #define MDIO_DATA_MASK			0x7fffffff
 #define MDIO_PORT_MASK			0xf0000
+#define MDIO_PORT_EXT_MASK		0x200000
 #define MDIO_REGAD_MASK			0xffff
-#define MDIO_CMD_MASK			0xfff00000
+#define MDIO_CMD_MASK			0x00100000
 #define MDIO_CMD_READ			0x1
 #define MDIO_CMD_WRITE			0x0
 #define MDIO_DATA_DONE_MASK		0x80000000
@@ -327,6 +328,7 @@ static u32 brcm_pcie_mdio_form_pkt(int port, int regad, int cmd)
 {
 	u32 pkt = 0;
 
+	pkt |= FIELD_PREP(MDIO_PORT_EXT_MASK, port >> 4);
 	pkt |= FIELD_PREP(MDIO_PORT_MASK, port);
 	pkt |= FIELD_PREP(MDIO_REGAD_MASK, regad);
 	pkt |= FIELD_PREP(MDIO_CMD_MASK, cmd);