gm107/ir: use scalar tex instructions where possible

gm107/ir: use scalar tex instructions where possible

TEXS, TLD4 and TLD4S are variants of tex instructions which are more
scalar, which gives RA more freedom and is less likely to insert silly
MOVs to satisfy quad registers.

shader-db changes:
total instructions in shared programs : 7687265 -> 7614782 (-0.94%)
total gprs used in shared programs    : 803620 -> 798045 (-0.69%)
total shared used in shared programs  : 639636 -> 639636 (0.00%)
total local used in shared programs   : 24648 -> 24648 (0.00%)
total bytes used in shared programs   : 82103400 -> 81330696 (-0.94%)

                local     shared        gpr       inst      bytes
    helped           0           0        3648       10647       10647
      hurt           0           0         464         205         205

Reviewed-by: Ilia Mirkin <imirkin@alum.mit.edu>