armv8: move low-level assembly functions into function-sections

TPL builds today don't need to call into firmware or set up the MMU
(if this changes, it should be controlled through a config option
whether to include this or not), but include the needed support code
for this anyway.  By moving these unused low-level functions into
seperate function-sections, the linker can garbage-collect the unused
sections.

Note that (if DM support is enabled), there will be a call to the
cache-flushing code from alloc_priv(...) in drivers/core/device.c.
This then add 52 bytes of binary size (an increase from 20589 to 20641
bytes) compared to completely removing this code.

Even for a feature-rich TPL (including DM support as for the RK3368),
this equates to a size difference of significantly more than 10% in
TPL binary size.

Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/arm/cpu/armv8/tlb.S b/arch/arm/cpu/armv8/tlb.S
index 945445b..6743111 100644
--- a/arch/arm/cpu/armv8/tlb.S
+++ b/arch/arm/cpu/armv8/tlb.S
@@ -14,7 +14,8 @@
  * void __asm_invalidate_tlb_all(void)
  *
  * invalidate all tlb entries.
- */
+*/
+.pushsection .text.__asm_invalidate_tlb_all, "ax"
 ENTRY(__asm_invalidate_tlb_all)
 	switch_el x9, 3f, 2f, 1f
 3:	tlbi	alle3
@@ -31,3 +32,4 @@
 0:
 	ret
 ENDPROC(__asm_invalidate_tlb_all)
+.popsection