spi: zynq_spi: Simplify debug macro

Trivial fix.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
diff --git a/drivers/spi/zynq_spi.c b/drivers/spi/zynq_spi.c
index 0208afc..7ae1f0e 100644
--- a/drivers/spi/zynq_spi.c
+++ b/drivers/spi/zynq_spi.c
@@ -79,7 +79,7 @@
 					250000000);
 	plat->speed_hz = plat->frequency / 2;
 
-	debug("zynq_spi_ofdata_to_platdata: regs=%p max-frequency=%d\n",
+	debug("%s: regs=%p max-frequency=%d\n", __func__,
 	      plat->regs, plat->frequency);
 
 	return 0;