phy: xgene: make array serdes_reg static const, makes object smaller

Don't populate the array serdes_reg on the stack but instead make it
static const. Makes the object code smaller by 228 bytes.

Before:
   text	   data	    bss	    dec	    hex	filename
  23875	   6232	     64	  30171	   75db	drivers/phy/phy-xgene.o

After:
   text	   data	    bss	    dec	    hex	filename
  23551	   6328	     64	  29943	   74f7	drivers/phy/phy-xgene.o

(gcc version 9.2.1, amd64)
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>

drivers/phy/phy-xgene.c

@@ -1342,7 +1342,7 @@ static int xgene_phy_hw_initialize(struct xgene_phy_ctx *ctx,
 static void xgene_phy_force_lat_summer_cal(struct xgene_phy_ctx *ctx, int lane)
 {
 	int i;
-	struct {
+	static const struct {
 		u32 reg;
 		u32 val;
 	} serdes_reg[] = {