arm: mvebu: ddr: Fix compilation warning

gcc 5.1 generates this new warning (for Armada 38x platforms):

drivers/ddr/marvell/a38x/ddr3_debug.c: In function 'hws_ddr3_tip_read_training_result':
drivers/ddr/marvell/a38x/ddr3_debug.c:177:40: warning: 'sizeof' on array
  function parameter 'result' will return size of 'enum hws_result (*)[1]' [-Wsizeof-array-argument]
  memcpy(result, training_result, sizeof(result));
                                        ^
drivers/ddr/marvell/a38x/ddr3_debug.c:171:31: note: declared here
  u32 dev_num, enum hws_result result[MAX_STAGE_LIMIT][MAX_INTERFACE_NUM])
                               ^

Since this functions is not referenced anywhere, lets just remove it.

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Luka Perkov <luka.perkov@sartura.hr>