Fix switched L/R / L2/R2 mappings for the Generic X-Box pad

L/R are buttons, L2/R2 are axes.
Also removed input_enable_hotkey_btn and input_exit_emulator_btn, they shouldn't be defined in the autoconfiguration IMO (and aren't in the other configs here).
Merge pull request #3 from prettyv/master

Fix switched L/R / L2/R2 mappings for the Generic X-Box pad