i2c: i801: Stop using pm_runtime_set_autosuspend_delay(-1)

i2c: i801: Stop using pm_runtime_set_autosuspend_delay(-1)

The original change works as intended, but Andy pointed in [0] that now
userspace could re-enable RPM via sysfs, even though we explicitly want
to disable it. So effectively revert the original patch, just with small
improvements:
- Calls to pm_runtime_allow()/pm_runtime_forbid() don't have to be
  balanced, so we can remove the call to pm_runtime_forbid() in
  i801_remove().
- priv->acpi_reserved is accessed after i801_acpi_remove(), and according
  to Robert [1] the custom handler can't run any longer. Therefore we
  don't have to take priv->acpi_lock.

[0] https://www.spinics.net/lists/linux-i2c/msg52730.html
[1] https://lore.kernel.org/linux-acpi/BYAPR11MB32561D19A0FD9AB93E2B1E5287D39@BYAPR11MB3256.namprd11.prod.outlook.com/T/#t

Fixes: 4e60d5dd10cd ("i2c: i801: Improve disabling runtime pm")
Reported-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Acked-by: Rafael J. Wysocki <rafael@kernel.org>
Reviewed-by: Jean Delvare <jdelvare@suse.de>
Signed-off-by: Wolfram Sang <wsa@kernel.org>