Fix W=1 warnings. Mark variables used for reads as __always_unused.

sound/pci/emu10k1/emu10k1_main.c: In function
‘snd_emu10k1_cardbus_init’:
sound/pci/emu10k1/emu10k1_main.c:626:15: warning: variable ‘value’ set
but not used [-Wunused-but-set-variable]
  626 |  unsigned int value;
      |               ^~~~~
sound/pci/emu10k1/emu10k1_main.c: In function
‘snd_emu1010_load_firmware_entry’:
sound/pci/emu10k1/emu10k1_main.c:656:15: warning: variable
‘write_post’ set but not used [-Wunused-but-set-variable]
  656 |  unsigned int write_post;
      |               ^~~~~~~~~~
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20200702193604.169059-12-pierre-louis.bossart@linux.intel.comSigned-off-by: Takashi Iwai <tiwai@suse.de>