Modifications towards full ipc

- Added a full ipc send/recv test
- Removed non-zero value checking in r2 for ipc that was there
  to catch inadvertent full ipc calls.
- Added correct hanlding for read/write mrs for current status of utcb.

TODO:
- Add mapping of every utcb to every task for privileged access so that
  the kernel can access every utcb without switching spaces.
- Removal of same mappings
- Upon thread creation need to copy page tables accordingly i.e.
  each task will have its own utcb mapped with USER access, but every
  other utcb as kernel access only. Need to handle this case upon page
  table copying.

tasks/libl4/src/arm/syscalls.S

@@ -63,10 +63,6 @@ BEGIN_PROC(arch_clone)
 	utcb_address r12		@ Get utcb address.
 	ldmia	r12!, {r3-r8}		@ Load 6 Message registers from utcb. MR0-MR5
 
-	cmp	r2, #0
-1:
-	bne	1b
-
 	ldr	r12, =__l4_ipc
 	mov	lr, pc
 	ldr	pc, [r12]		@ Perform the ipc()
@@ -106,11 +102,6 @@ BEGIN_PROC(l4_ipc)
 	stmfd	sp!, {r4-r8,lr}		@ Save context.
 	utcb_address r12		@ Get utcb address.
 	ldmia	r12!, {r3-r8}		@ Load 6 Message registers from utcb. MR0-MR5
-
-	cmp	r2, #0
-1:
-	bne	1b
-
 	ldr	r12, =__l4_ipc
 	mov	lr, pc
 	ldr	pc, [r12]