[LSR] Fixup canonicalization formula and its checker.

According to definition of canonical form, it is a canonical
if scale reg does not contain addrec for loop L then none of bases
should contain addrec for this loop.

The critical word here is "contains".

Current checker of canonical form checks not "containing" property
but "is". So it does not check whether it contains but whether it is.

Fix the checker and canonicalizing utility to follow definition.

Without this fix in the test attached the base formula looking as
reg((-1 * {0,+,8}<nuw><nsw><%bb2>)<nsw>) + 1*reg((8 * (%arg /u 8))<nuw>)
is considered as conanocial while base contains an addrec.
And modified formula we want to insert
reg({0,+,8}<nuw><nsw><%bb2>) + 1*reg((-8 * (%arg /u 8)))
is considered as not canonical.

Reviewed By: mkazantsev
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D122457