Hexagon: fix outdated `hex_new_*` comments

Hexagon: fix outdated `hex_new_*` comments

Some code comments refer to hex_new_value and hex_new_pred_value, which
have been transferred to DisasContext and, in the case of hex_new_value,
should now be accessed through get_result_gpr().

In order to fix this outdated comments and also avoid having to tweak
them whenever we make a variable name change in the future, let's
replace them with pseudocode.

Suggested-by: Taylor Simpson <tsimpson@quicinc.com>
Signed-off-by: Matheus Tavares Bernardino <quic_mathbern@quicinc.com>
Reviewed-by: Taylor Simpson <tsimpson@quicinc.com>
Signed-off-by: Taylor Simpson <tsimpson@quicinc.com>
Message-Id: <8e1689e28dd7b1318369b55127cf47b82ab75921.1684939078.git.quic_mathbern@quicinc.com>