package/lvm2: drop BR2_PACKAGE_LVM2_APP_LIBRARY

package/lvm2: drop BR2_PACKAGE_LVM2_APP_LIBRARY

The application library (liblvm2app) has been dropped since version
2.03.00 and
https://github.com/lvmteam/lvm2/commit/0d22b58172808f050abeacdb5d6a7b7132b91a8c

It should be noted that lvm2 support must be dropped from udisks until
a bump to at least version 2.7.0 and
https://github.com/storaged-project/udisks/commit/4c0709a893be49a0db5b2839e4766621e2c1bb98

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
[yann.morin.1998@free.fr:
  - slightly expand help text for legacy BR2_PACKAGE_UDISKS_LVM2
]
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>