[NFC][AArch64] Replace some template methods/invocations...

...with the non-template version, as the template version might
increase the size of the compiler build.

Methods affected:

1.`findAddrModeSVELoadStore`
2. `SelectPredicatedStore`

Also, remove the `const` qualifier from the `unsigned` parameters of
the methods to conform with other similar methods in the class.

(cherry picked from commit dbeb184b)