Fix flags collision causing inability to enable CBQ in ALTQ

The CBQ BORROW flag conflicts with the RMCF_CODEL flag; the
two sets of definitions actually define the same things. The symptom
is that a kernel with CBQ support and not CODEL fails to load a QoS
policy with the obscure error "pfctl: DIOCADDALTQ: Cannot allocate memory."
If ALTQ_DEBUG is enabled, the error becomes a little clearer:
"rmc_newclass: CODEL not configured for CBQ!" is printed by the kernel.
There really shouldn't be two sets of macros that have to be defined
consistently, but the include structure isn't right for exporting
CBQ flags to altq_rmclass.h. Re-align the definitions, and add
CTASSERTs in the kernel to ensure that the definitions are consistent.

PR: 215716
Reviewed by: pkelsey
MFC after: 2 weeks
Sponsored by: Forcepoint LLC
Differential Revision: https://reviews.freebsd.org/D17758