So, i was install trunk version of OpenWRT. This solve problem with flashing firmware for Archer C7 ac1750 with new gd25q128. SSH connect successfuly .
Next question: can i patch OpenWRT ImageBuilder 15.04 (stable, not trunk) for my router (with gd25q128) ?
No, imagebuilder process starts with a prebuilt kernel that doesn't have the chip id mentioned in the driver that's linked into it.
You need to build the kernel from source, and the rest of the openwrt image from source.