Bug when setting up default partitioning,
used an uninitialized variabe.

mysql-test/r/partition.result:
  Bug#48276: can't add column if subpartition exists
  
  Added result
mysql-test/t/partition.test:
  Bug#48276: can't add column if subpartition exists
  
  Added test
sql/sql_partition.cc:
  Bug#48276: can't add column if subpartition exists
  
  even if is_create_table_ind was set, one tried to set no_subparts
  with the unitialized no_parts local variable.
  
  Fixed by rearrange the code to be to only execute
  the statements when is_create_table_ind was not set.