When the CLI command wifitool athX disable_opclass_chans is executed
with a valid 20 MHz operating class, the command throws an error,
"Opclass should only be 20 MHz opclass" on the console.
The opclass passed as an argument to reg_enable_disable_opclass_chans,
which is greater than 20 MHz in value, makes the API reg_is_20mhz_opclass,
always return false.
To fix the issue, pass channel spacing (in MHz units) as an argument to
the 'reg_is_20mhz_opclass'. Also rename 'reg_is_20mhz_opclass' to
'reg_is_chanspacing_20mhz' as we are verifying if the channel spacing
of an opclass is close to 20 MHz; not verifying the opclass itself.
Change-Id: I198b4d90c68613210377b96f6836c5b8c810dc7f
CRs-Fixed: 3410934
aecdfaa78a