net: macb: Update gem PTP support check

There are currently two checks for PTP functionality - one on GEM
capability and another on the kernel config option. Combine them
into a single function as there's no use case where gem_has_ptp is
TRUE and MACB_USE_HWSTAMP is false.
Signed-off-by: Harini Katakam <harini.katakam@amd.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/cadence/macb.h

@@ -1363,7 +1363,7 @@ static inline bool macb_is_gem(struct macb *bp)
 
 static inline bool gem_has_ptp(struct macb *bp)
 {
-	return !!(bp->caps & MACB_CAPS_GEM_HAS_PTP);
+	return IS_ENABLED(CONFIG_MACB_USE_HWSTAMP) && (bp->caps & MACB_CAPS_GEM_HAS_PTP);
 }
 
 /**

drivers/net/ethernet/cadence/macb_main.c

@@ -3893,17 +3893,17 @@ static void macb_configure_caps(struct macb *bp,
 		dcfg = gem_readl(bp, DCFG2);
 		if ((dcfg & (GEM_BIT(RX_PKT_BUFF) | GEM_BIT(TX_PKT_BUFF))) == 0)
 			bp->caps |= MACB_CAPS_FIFO_MODE;
-#ifdef CONFIG_MACB_USE_HWSTAMP
 		if (gem_has_ptp(bp)) {
 			if (!GEM_BFEXT(TSU, gem_readl(bp, DCFG5)))
 				dev_err(&bp->pdev->dev,
 					"GEM doesn't support hardware ptp.\n");
 			else {
+#ifdef CONFIG_MACB_USE_HWSTAMP
 				bp->hw_dma_cap |= HW_DMA_CAP_PTP;
 				bp->ptp_info = &gem_ptp_info;
+#endif
 			}
 		}
-#endif
 	}
 
 	dev_dbg(&bp->pdev->dev, "Cadence caps 0x%08x\n", bp->caps);