Allow selection of higher rank tests using --target-rank

 * The default rank range has been increased from 1-4 to 1-6.
 * Higher ranks often make tests too large so a default_test_rank_range
has been included which makes the test generator produce only tests with
ranks 1-4.
 * The user can now specify target-rank up to rank 6 which is allowed
for all operators with the default rank range.
 * The maximum rank allowed (6) stored in TOSA_TENSOR_MAX_RANK variable.
 * User specified target shapes up to maximum rank are accepted without
need for setting target-rank filter.

Signed-off-by: Jeremy Johnson <jeremy.johnson@arm.com>
Change-Id: Ie4ca408d329cb1000ce9d3592b2c7d62bf311b3b