ptp: describe the two disables in ptp_set_pinfunc()

ptp: describe the two disables in ptp_set_pinfunc()

Accurately describe what each call to ptp_disable_pinfunc() is doing,
rather than the misleading comment above the first disable. This helps
to make the code more readable.

Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Vadim Fedorenko <vadim.fedorenko@linux.dev>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Acked-by: Richard Cochran <richardcochran@gmail.com>
Link: https://patch.msgid.link/E1uydLC-000000061DG-2BRt@rmk-PC.armlinux.org.uk
Signed-off-by: Jakub Kicinski <kuba@kernel.org>