Address the comments and fix failing tests

AArch64/machine-licm-hoist-load.ll - added memcmp-sized 6 test, comments, removed irrelevant lines and from AArch64/machine-licm-hoist-load.ll

AArch64/sinksplat.ll, AArch64/zext-to-tbl.ll - regenerated check lines without `-hoist-const-loads=false`

Adjusted tests after seeing that manually hoisted load results in the same assembly as the code where MachineLICM does this job:
* Hexagon/reg-scavengebug-2.ll
* Mips/lcb5.ll
* Hexagon/swp-const-tc2.ll (added `-hoist-const-loads=false` flag as I am unsure about the test's purpose)

Author: igogo-x86