ltq-atm: fix missing-prototypes warnings for lantiq/ase

ltq-atm: fix missing-prototypes warnings for lantiq/ase

This patch fixes various missing-prototypes build warnings on
6.12 kernel.

/home/db/owrt/build_dir/target-mips_24kc_musl/linux-lantiq_ase/ltq-atm-ase/ltq-atm/ifxmips_atm_amazon_se.c:257:13: error: no previous prototype for 'ase_fw_ver' [-Werror=missing-prototypes]
  257 | extern void ase_fw_ver(unsigned int *major, unsigned int *minor)
      |             ^~~~~~~~~~
/home/db/owrt/build_dir/target-mips_24kc_musl/linux-lantiq_ase/ltq-atm-ase/ltq-atm/ifxmips_atm_amazon_se.c:266:5: error: no previous prototype for 'ase_init' [-Werror=missing-prototypes]
  266 | int ase_init(struct platform_device *pdev)
      |     ^~~~~~~~
/home/db/owrt/build_dir/target-mips_24kc_musl/linux-lantiq_ase/ltq-atm-ase/ltq-atm/ifxmips_atm_amazon_se.c:283:6: error: no previous prototype for 'ase_shutdown' [-Werror=missing-prototypes]
  283 | void ase_shutdown(void)
      |      ^~~~~~~~~~~~
/home/db/owrt/build_dir/target-mips_24kc_musl/linux-lantiq_ase/ltq-atm-ase/ltq-atm/ifxmips_atm_amazon_se.c:297:5: error: no previous prototype for 'ase_start' [-Werror=missing-prototypes]
  297 | int ase_start(int pp32)
      |     ^~~~~~~~~
/home/db/owrt/build_dir/target-mips_24kc_musl/linux-lantiq_ase/ltq-atm-ase/ltq-atm/ifxmips_atm_amazon_se.c:323:6: error: no previous prototype for 'ase_stop' [-Werror=missing-prototypes]
  323 | void ase_stop(int pp32)
      |      ^~~~~~~~

Signed-off-by: Shiji Yang <yangshiji66@outlook.com>
Link: https://github.com/openwrt/openwrt/pull/18744
Signed-off-by: Robert Marko <robimarko@gmail.com>