lib/bootmem: Introduce custom bootmem tags

Introduce bootmem custom memory tags and use them instead of reusing
LB_MEM tags.
Use asserts in bootmem_add_range to verify parameters.

Tested with uImage payload on Cavium SoC.

Change-Id: I7be8fa792fc7933ca218ecd43d250d3a9c55caa6
Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Reviewed-on: https://review.coreboot.org/25633
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>

src/arch/x86/tables.c

@@ -266,5 +266,5 @@ void bootmem_arch_add_ranges(void)
 	/* Memory from 0 through the forwarding_table is reserved. */
 	const uintptr_t base = 0;
 
-	bootmem_add_range(base, forwarding_table - base, LB_MEM_TABLE);
+	bootmem_add_range(base, forwarding_table - base, BM_MEM_TABLE);
 }