Fix pioasm generating an enum member which doesn't match pio.h

[KewlKris]

When including the .mov_status directive to configure STATUS based on an IRQ flag (ex: .mov_status irq set 0), pioasm generates code with a reference to "STATUS_IRQ_INDEX", but this is different from the member name as defined in pio.h.

This generated the following code:

sm_config_set_mov_status(&c, STATUS_IRQ_INDEX, 0);

And thus caused the compile error:

error: 'STATUS_IRQ_INDEX' undeclared (first use in this function); did you mean 'STATUS_IRQ_SET'?

This fix changes the generated name so it matches the enum.