phy: sr-usb: Constify phy_ops

phy_ops are never modified and can therefore be made const to allow the
compiler to put it in read-only memory.

Before:
   text    data     bss     dec     hex filename
   4310    1244       0    5554    15b2 drivers/phy/broadcom/phy-bcm-sr-usb.o

After:
   text    data     bss     dec     hex filename
   4438    1116       0    5554    15b2 drivers/phy/broadcom/phy-bcm-sr-usb.o
Signed-off-by: Rikard Falkeborn <rikard.falkeborn@gmail.com>
Link: https://lore.kernel.org/r/20200516120441.7627-3-rikard.falkeborn@gmail.comSigned-off-by: Kishon Vijay Abraham I <kishon@ti.com>

drivers/phy/broadcom/phy-bcm-sr-usb.c

@@ -256,7 +256,7 @@ static int bcm_usb_phy_init(struct phy *phy)
 	return ret;
 }
 
-static struct phy_ops sr_phy_ops = {
+static const struct phy_ops sr_phy_ops = {
 	.init		= bcm_usb_phy_init,
 	.reset		= bcm_usb_phy_reset,
 	.owner		= THIS_MODULE,