arm: remove TTB_SECT_XN_MASK in DCACHE_WRITETHROUGH

The normal memory (other that DCACHE_OFF) should be executable by default,
only the device memory (DCACHE_OFF) used for peripheral access should have
the bit execute never (TTB_SECT_XN_MASK).

Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>

arch/arm/include/asm/system.h

@@ -489,7 +489,7 @@ enum dcache_option {
  */
 enum dcache_option {
 	DCACHE_OFF = TTB_SECT_DOMAIN(0) | TTB_SECT_XN_MASK | TTB_SECT,
-	DCACHE_WRITETHROUGH = DCACHE_OFF | TTB_SECT_C_MASK,
+	DCACHE_WRITETHROUGH = TTB_SECT_DOMAIN(0) | TTB_SECT | TTB_SECT_C_MASK,
 	DCACHE_WRITEBACK = DCACHE_WRITETHROUGH | TTB_SECT_B_MASK,
 	DCACHE_WRITEALLOC = DCACHE_WRITEBACK | TTB_SECT_TEX(1),
 };