Set bitmap block size to page size

kernel/bitmap/bitmap.h

@@ -5,6 +5,8 @@
 #include <stddef.h>
 #include <stdbool.h>
 
+#include "hal/hal.h"
+
 typedef struct {
   uint8_t *map;
   size_t nblocks;
@@ -15,7 +17,7 @@ typedef struct {
 } BitMap;
 
 #define BITMAP_BLOCKS_PER_BYTE 8
-#define BITMAP_BLOCK_SIZE 0x1000
+#define BITMAP_BLOCK_SIZE HAL_PAGE_SIZE
 #define BITMAP_INVALID_BLOCK ((size_t)-1)
 
 void *bitmap_toptr(BitMap *bm, size_t block);