pcmanfm: bump version to 1.2.3

- Bump version to 1.2.3
- Remove unnecessary patch
- Add a hash file

[Thomas:
 - adapt patch to the latest master
 - license is GPLv2+, not GPLv2
 - replace 'select BR2_PACKAGE_XORG7' by 'depends on BR2_PACKAGE_XORG7']

Signed-off-by: Vicente Olivert Riera <Vincent.Riera@imgtec.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>