tqm834x.c: fix compiler warning

Fix:

tqm834x.c:299: warning: passing argument 1 of 'get_ram_size' discards
qualifiers from pointer target type

Signed-off-by: Wolfgang Denk <wd@denx.de>
Acked-by: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Kim Phillips <kim.phillips@freescale.com>