[umalloc] Remove userptr_t from user memory allocations

Use standard void pointers for umalloc(), urealloc(), and ufree(),
with the "u" prefix retained to indicate that these allocations are
made from external ("user") memory rather than from the internal heap.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/interface/linux/linux_umalloc.c

@@ -31,9 +31,6 @@ FILE_LICENCE(GPL2_OR_LATER);
 
 #include <ipxe/linux_api.h>
 
-/** Special address returned for empty allocations */
-#define NOWHERE ((void *)-1)
-
 /** Poison to make the metadata more unique */
 #define POISON 0xa5a5a5a5
 #define min(a,b) (((a)<(b))?(a):(b))
@@ -47,7 +44,16 @@ struct metadata
 
 #define SIZE_MD (sizeof(struct metadata))
 
-/** Simple realloc which passes most of the work to mmap(), mremap() and munmap() */
+/**
+ * Reallocate external memory
+ *
+ * @v old_ptr		Memory previously allocated by umalloc(), or NULL
+ * @v new_size		Requested size
+ * @ret new_ptr		Allocated memory, or NULL
+ *
+ * Calling realloc() with a new size of zero is a valid way to free a
+ * memory block.
+ */
 static void * linux_realloc(void *ptr, size_t size)
 {
 	struct metadata md = {0, 0};
@@ -136,19 +142,4 @@ static void * linux_realloc(void *ptr, size_t size)
 	return ptr;
 }
 
-/**
- * Reallocate external memory
- *
- * @v old_ptr		Memory previously allocated by umalloc(), or UNULL
- * @v new_size		Requested size
- * @ret new_ptr		Allocated memory, or UNULL
- *
- * Calling realloc() with a new size of zero is a valid way to free a
- * memory block.
- */
-static userptr_t linux_urealloc(userptr_t old_ptr, size_t new_size)
-{
-	return (userptr_t)linux_realloc((void *)old_ptr, new_size);
-}
-
-PROVIDE_UMALLOC(linux, urealloc, linux_urealloc);
+PROVIDE_UMALLOC(linux, urealloc, linux_realloc);