Fix misleading indentation warning in group_sync_read.c

[de-vri-es]

GCC 6 warns about misleading indentation: code that appears to be guarded by an if-statement based on indentation, but actually isn't. That caused the warning below to appear with GCC 6. This PR adjust the indentation to fix the warning.

gcc -O2 -O3 -DLINUX -D_GNU_SOURCE -Wall -c -I../../include -m64 -fPIC -g -c ../../src/dynamixel_sdk/group_sync_read.c -o .objects/group_sync_read.o
../../src/dynamixel_sdk/group_sync_read.c: In function ‘groupSyncReadRxPacket’:
../../src/dynamixel_sdk/group_sync_read.c:257:5: warning: this ‘if’ clause does not guard... [-Wmisleading-indentation]
     if (groupData[group_num].data_list[data_num].id == NOT_USED_ID)
     ^~
../../src/dynamixel_sdk/group_sync_read.c:260:7: note: ...this statement, but the latter is misleadingly indented as if it is guarded by the ‘if’
       packetData[port_num].data_read

[LeonJung]

Thank you

[de-vri-es]

Awesome, thanks