To make runalltests.sh configurable for default tests

To make runalltests.sh configurable for default tests

This patch applied to ltp runalltests.sh script to make default set of test
 suits configurable which is not the default behaviour.
 By default rullalltests.sh invokes runltp wihout specifying any set of tests
 to run. This patch will give the user option to chose from defaults suits
 setting their respective variables named RUN_DEFAULT_SUITENAME to '0' or '1'.
 Thus executing only desired suites.

Signed-off-by: Irfan Sadiq <irfan_sadiq@mentor.com>
Signed-off-by: Khem Raj <raj.khem@gmail.com>