core: read: add dev_read_addr_size_index_ptr function

Add dev_read_addr_size_index_ptr function with the same functionality as
dev_read_addr_size_index, but instead a return pointer is given.
Use map_sysmem() function as cast for the return.

Signed-off-by: Jonas Karlman <jonas@kwiboo.se>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>