44x_spd_ddr2.c: Fix GCC 4.6 build warnings

44x_spd_ddr2.c: Fix GCC 4.6 build warnings

44x_spd_ddr2.c: In function 'initdram':
44x_spd_ddr2.c:450:17: warning: variable 'dimm_spd' set but not used [-Wunused-but-set-variable]
44x_spd_ddr2.c: In function 'program_copt1':
44x_spd_ddr2.c:1003:16: warning: variable 'ddrtype' set but not used [-Wunused-but-set-variable]
44x_spd_ddr2.c: In function 'DQS_calibration_process':
44x_spd_ddr2.c:2498:7: warning: variable 'window_found' set but not used [-Wunused-but-set-variable]
44x_spd_ddr2.c:2497:16: warning: variable 'end_rffd' set but not used [-Wunused-but-set-variable]
44x_spd_ddr2.c:2496:16: warning: variable 'end_rqfd' set but not used [-Wunused-but-set-variable]
44x_spd_ddr2.c:2495:16: warning: variable 'begin_rffd' set but not used [-Wunused-but-set-variable]
44x_spd_ddr2.c:2494:16: warning: variable 'begin_rqfd' set but not used [-Wunused-but-set-variable]
44x_spd_ddr2.c:2493:7: warning: variable 'min_end' set but not used [-Wunused-but-set-variable]

Signed-off-by: Stefan Roese <sr@denx.de>