ddr: altera: sequencer: Wrap ac_rom_init and inst_rom_init

Introduce two wrapper functions, socfpga_get_seq_ac_init() and
socfpga_get_seq_inst_init() to avoid direct inclusion of the
sequencer_auto_ac_init.h and sequencer_auto_inst_init.h QTS
generated files. This reduces namespace pollution again.

Signed-off-by: Marek Vasut <marex@denx.de>
Acked-by: Dinh Nguyen <dinguyen@opensource.altera.com>