[ALSA] sound: ca0106_main.c fix shadowed variable warnings

change to intr_enable as per the two functions it is defined in.
sound/pci/ca0106/ca0106_main.c:438:15: warning: symbol 'enable' shadows an earlier one
sound/pci/ca0106/ca0106_main.c:159:12: originally declared here
sound/pci/ca0106/ca0106_main.c:449:15: warning: symbol 'enable' shadows an earlier one
sound/pci/ca0106/ca0106_main.c:159:12: originally declared here

Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>