selinux,smack: remove the capability checks in the removexattr hooks

Commit 61df7b82 ("lsm: fixup the inode xattr capability handling")
moved the responsibility of doing the inode xattr capability checking
out of the individual LSMs and into the LSM framework itself.
Unfortunately, while the original commit added the capability checks
to both the setxattr and removexattr code in the LSM framework, it
only removed the setxattr capability checks from the individual LSMs,
leaving duplicated removexattr capability checks in both the SELinux
and Smack code.

This patch removes the duplicated code from SELinux and Smack.

Fixes: 61df7b82 ("lsm: fixup the inode xattr capability handling")
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>