fix(drivers/mtd): macronix quad enable bit issue

Invert test logic on the status register control to
fix issue when the bit SR_QUAD_EN_MX is not set.

Change-Id: I8b2f140219f124336bf96462abf9d9445d0308bc
Signed-off-by: Lionel Debieve <lionel.debieve@st.com>
Signed-off-by: Yann Gautier <yann.gautier@st.com>

drivers/mtd/nor/spi_nor.c

@@ -131,7 +131,7 @@ static int spi_nor_macronix_quad_enable(void)
 		return ret;
 	}
 
-	if ((sr & SR_QUAD_EN_MX) == 0U) {
+	if ((sr & SR_QUAD_EN_MX) != 0U) {
 		return 0;
 	}