soc/amd/common/espi: Clear DNCMD_COMPLETE on completion

Tidy up the interrupt status. This will leave SLAVE0_INT_STS = 0.

BUG=b:183524609
TEST=Boot guybrush to OS

Signed-off-by: Raul E Rangel <rrangel@chromium.org>
Change-Id: I950cfb81521e35758c120a482670cfdb924201d2
Reviewed-on: https://review.coreboot.org/c/coreboot/+/52056
Reviewed-by: Furquan Shaikh <furquan@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/soc/amd/common/block/lpc/espi_util.c

@@ -519,6 +519,8 @@ static int espi_send_command(const struct espi_cmd *cmd)
 		return -1;
 	}
 
+	espi_write32(ESPI_SLAVE0_INT_STS, ESPI_STATUS_DNCMD_COMPLETE);
+
 	return 0;
 }