According to Kernel comment, no one checks the return value of routines:
debugfs_create_u8
debugfs_create_u16
debugfs_create_u32
debugfs_create_u64
debugfs_create_atomic_t
so remove return value of related qdf api.
Change-Id: I7d260bccfce463dddae963c54a776813df116eac
CRs-Fixed: 2666506