system/physmem: remove redundant arg reassignment

Arguments `ram_block` are reassigned to local declarations `block`
without further use. Remove re-assignment to reduce noise.

Signed-off-by: Manos Pitsidianakis <manos.pitsidianakis@linaro.org>
Reviewed-by: Michael Tokarev <mjt@tls.msk.ru>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

system/physmem.c

@@ -2154,10 +2154,8 @@ void qemu_ram_remap(ram_addr_t addr, ram_addr_t length)
  *
  * Called within RCU critical section.
  */
-void *qemu_map_ram_ptr(RAMBlock *ram_block, ram_addr_t addr)
+void *qemu_map_ram_ptr(RAMBlock *block, ram_addr_t addr)
 {
-    RAMBlock *block = ram_block;
-
     if (block == NULL) {
         block = qemu_get_ram_block(addr);
         addr -= block->offset;
@@ -2182,10 +2180,9 @@ void *qemu_map_ram_ptr(RAMBlock *ram_block, ram_addr_t addr)
  *
  * Called within RCU critical section.
  */
-static void *qemu_ram_ptr_length(RAMBlock *ram_block, ram_addr_t addr,
+static void *qemu_ram_ptr_length(RAMBlock *block, ram_addr_t addr,
                                  hwaddr *size, bool lock)
 {
-    RAMBlock *block = ram_block;
     if (*size == 0) {
         return NULL;
     }