[SPARC64]: Simplify TSB insert checks.

Don't try to avoid putting non-base page sized entries
into the user TSB.  It actually costs us more to check
this than it helps.

Eventually we'll have a multiple TSB scheme for user
processes.  Once a process starts using larger pages,
we'll allocate and use such a TSB.

Signed-off-by: David S. Miller <davem@davemloft.net>