You need to update the RetroPie Setup Script first. To do so, change to the directory of RetroPie Setup Script,
and update the script via git,
Then, start the setup script via
change to source-based installation and select only the GBA emulator gpsp to be installed.
Afterwards, re-enerate the Emulation Station configuration file from the “setup” menu.
I have written this without explicit testing, please report any issues that possibly occur.
Hope that helps!