exec.c: subpage->sub_section is already initialized to 0

In subpage_init(), we will set subpage->sub_section to
PHYS_SECTION_UNASSIGNED by subpage_register. Since
PHYS_SECTION_UNASSIGNED is defined to be 0, and we allocate subpage with
g_malloc0, this means subpage->sub_section is already initialized to 0.

This patch removes the redundant setup for a new subpage and also fix
the code style.
Signed-off-by: NWei Yang <richardw.yang@linux.intel.com>
Message-Id: <20190321082555.21118-5-richardw.yang@linux.intel.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

exec.c

@@ -1491,7 +1491,7 @@ hwaddr memory_region_section_get_iotlb(CPUState *cpu,
 
 #if !defined(CONFIG_USER_ONLY)
 
-static int subpage_register (subpage_t *mmio, uint32_t start, uint32_t end,
+static int subpage_register(subpage_t *mmio, uint32_t start, uint32_t end,
                             uint16_t section);
 static subpage_t *subpage_init(FlatView *fv, hwaddr base);
 
@@ -2913,7 +2913,7 @@ static const MemoryRegionOps subpage_ops = {
     .endianness = DEVICE_NATIVE_ENDIAN,
 };
 
-static int subpage_register (subpage_t *mmio, uint32_t start, uint32_t end,
+static int subpage_register(subpage_t *mmio, uint32_t start, uint32_t end,
                             uint16_t section)
 {
     int idx, eidx;
@@ -2937,6 +2937,7 @@ static subpage_t *subpage_init(FlatView *fv, hwaddr base)
 {
     subpage_t *mmio;
 
+    /* mmio->sub_section is set to PHYS_SECTION_UNASSIGNED with g_malloc0 */
     mmio = g_malloc0(sizeof(subpage_t) + TARGET_PAGE_SIZE * sizeof(uint16_t));
     mmio->fv = fv;
     mmio->base = base;
@@ -2947,7 +2948,6 @@ static subpage_t *subpage_init(FlatView *fv, hwaddr base)
     printf("%s: %p base " TARGET_FMT_plx " len %08x\n", __func__,
            mmio, base, TARGET_PAGE_SIZE);
 #endif
-    subpage_register(mmio, 0, TARGET_PAGE_SIZE-1, PHYS_SECTION_UNASSIGNED);
 
     return mmio;
 }