ffplay: only use hardware accelerated SDL texture formats

ffplay: only use hardware accelerated SDL texture formats

Typically only a small subset of the SDL texture formats are supported directly
by the SDL renderer drivers, the rest is software emulated. It's better if
libswscale does the format conversion to a hardware-accelerated texture format
instead of SDL.

This should fix video render slowdowns with some texture formats after
3bd2228d05a05eab5f91ac00b01efac9cb07649b.

Signed-off-by: Marton Balint <cus@passwd.hu>