To be able keep the temporary register in the type independent NRM
instruction, the vertex temporary register is renamed to TA to match
the name of a pixel shader register.

This shortens the code and reduces the amount of temp regs used by 1.

texm3x2pad knows which register the following texm3x2depth or tex instruction
will use, and it knows that this register is uninitialized. So use it for
temporary storage instead of TMP.