staging: ks7010: ks_hostif: Remove a bunch of unused variables

staging: ks7010: ks_hostif: Remove a bunch of unused variables

Add comments to preserve documentation.

Fixes the following W=1 kernel build warning(s):

 drivers/staging/ks7010/ks_hostif.c: In function ‘hostif_mib_get_confirm’:
 drivers/staging/ks7010/ks_hostif.c:528:6: warning: variable ‘mib_val_type’ set but not used [-Wunused-but-set-variable]
 drivers/staging/ks7010/ks_hostif.c:527:6: warning: variable ‘mib_val_size’ set but not used [-Wunused-but-set-variable]
 drivers/staging/ks7010/ks_hostif.c: In function ‘hostif_infrastructure_set_confirm’:
 drivers/staging/ks7010/ks_hostif.c:849:6: warning: variable ‘result_code’ set but not used [-Wunused-but-set-variable]
 drivers/staging/ks7010/ks_hostif.c: In function ‘hostif_phy_information_confirm’:
 drivers/staging/ks7010/ks_hostif.c:929:19: warning: variable ‘noise’ set but not used [-Wunused-but-set-variable]

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-staging@lists.linux.dev
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20210414181129.1628598-24-lee.jones@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>