[ALSA] sound/isa/: cleanups

GUS Library
This patch contains the following possible cleanups:
- make needlesly global code static
- #if 0 the following unused global functions:
  - gus/gus_volume.c: snd_gf1_gvol_to_lvol_raw
  - gus/gus_volume.c: snd_gf1_calc_ramp_rate
  - gus/gus_volume.c: snd_gf1_compute_vibrato
  - gus/gus_volume.c: snd_gf1_compute_pitchbend
  - gus/gus_volume.c: snd_gf1_compute_freq
  - gus/gus_io.c: snd_gf1_i_adlib_write
  - gus/gus_io.c: snd_gf1_i_write_addr
  - gus/gus_io.c: snd_gf1_pokew
  - gus/gus_io.c: snd_gf1_peekw
  - gus/gus_io.c: snd_gf1_dram_setmem
  - gus/gus_io.c: snd_gf1_print_global_registers
  - gus/gus_io.c: snd_gf1_print_setup_registers
  - gus/gus_io.c: snd_gf1_peek_print_block
  - gus/gus_io.c: snd_gf1_print_setup_registers
  - gus/gus_io.c: snd_gf1_peek_print_block
- #if 0 the following unused global variable:
  - gus/gus_tables.h: snd_gf1_scale_table
- remove the following unneeded EXPORT_SYMBOL's:
  - gus/gus_main.c: snd_gf1_i_write16
  - gus/gus_main.c: snd_gf1_start
  - gus/gus_main.c: snd_gf1_stop

Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>