lmb: do away with arch_lmb_reserve()

All of the current definitions of arch_lmb_reserve() are doing the
same thing -- reserve the region of memory occupied by U-Boot,
starting from the current stack address to the ram_top. Introduce a
function lmb_reserve_uboot_region() which does this, and do away with
the arch_lmb_reserve() function.

Instead of using the current value of stack pointer for starting the
reserved region, have a fixed value, considering the stack size config
value.

Signed-off-by: Sughosh Ganu <sughosh.ganu@linaro.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
Acked-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>

arch/sh/lib/bootm.c

@@ -101,16 +101,3 @@ int do_bootm_linux(int flag, struct bootm_info *bmi)
 	/* does not return */
 	return 1;
 }
-
-static ulong get_sp(void)
-{
-	ulong ret;
-
-	asm("mov r15, %0" : "=r"(ret) : );
-	return ret;
-}
-
-void arch_lmb_reserve(void)
-{
-	arch_lmb_reserve_generic(get_sp(), gd->ram_top, 4096);
-}