make munmap free physical pages, and one correction for aligned mmap in syscall.c (extend_process_region is called with memory-region start-address which is aligned (map_end_aligned), instead of tail-address of current-region (region->map_end)) for aligned mmap (in syscall.c)

kernel/include/page.h

@@ -2,6 +2,7 @@
 #define __HEADER_PAGE_H
 
 void *allocate_pages(int npages, enum aal_mc_ap_flag flag);
+void free_pages_pa(unsigned long pa, int npages);
 void free_pages(void *va, int npages);
 
 #endif