driver: net: fsl-mc: Check NULL before pointer dereference

NULL pointer should be checked before any dereference.  This patch
move memest after the NULL pointer check.

Signed-off-by: Prabhakar Kushwaha <prabhakar.kushwaha@nxp.com>
Reported-by: Jose Rivera <german.rivera@nxp.com>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>
Reviewed-by: York Sun <york.sun@nxp.com>

drivers/net/fsl-mc/dpio/qbman_sys.h

@@ -255,11 +255,11 @@ static inline int qbman_swp_sys_init(struct qbman_swp_sys *s,
 	s->addr_cena = d->cena_bar;
 	s->addr_cinh = d->cinh_bar;
 	s->cena = (void *)valloc(CONFIG_SYS_PAGE_SIZE);
-	memset((void *)s->cena, 0x00, CONFIG_SYS_PAGE_SIZE);
 	if (!s->cena) {
 		printf("Could not allocate page for cena shadow\n");
 		return -1;
 	}
+	memset((void *)s->cena, 0x00, CONFIG_SYS_PAGE_SIZE);
 
 #ifdef QBMAN_CHECKING
 	/* We should never be asked to initialise for a portal that isn't in