um: Eliminate null test after alloc_bootmem

alloc_bootmem function never returns NULL. Thus a NULL test after a
call to this function is unnecessary.

The Coccinelle semantic patch used to make this change is follows:
@@
expression E;
statement S;
@@

E =
alloc_bootmem(...)
... when != E
- if (E == NULL) S

Signed-off-by: Amitoj Kaur Chawla <amitoj1606@gmail.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

arch/um/kernel/initrd.c

@@ -37,8 +37,6 @@ static int __init read_initrd(void)
 	}
 
 	area = alloc_bootmem(size);
-	if (area == NULL)
-		return 0;
 
 	if (load_initrd(initrd, area, size) == -1)
 		return 0;