Optimize mul in the zba extension with SH*ADD

This patch does the following optimization of mul with a constant.

(mul x, 11) -> (SH1ADD (SH2ADD x, x), x)
(mul x, 19) -> (SH1ADD (SH3ADD x, x), x)
(mul x, 13) -> (SH2ADD (SH1ADD x, x), x)
(mul x, 21) -> (SH2ADD (SH2ADD x, x), x)
(mul x, 37) -> (SH2ADD (SH3ADD x, x), x)
(mul x, 25) -> (SH3ADD (SH1ADD x, x), x)
(mul x, 41) -> (SH3ADD (SH2ADD x, x), x)
(mul x, 73) -> (SH3ADD (SH3ADD x, x), x)
(mul x, 27) -> (SH1ADD (SH3ADD x, x), (SH3ADD x, x))
(mul x, 45) -> (SH2ADD (SH3ADD x, x), (SH3ADD x, x))
(mul x, 81) -> (SH3ADD (SH3ADD x, x), (SH3ADD x, x))

Reviewed By: craig.topper

Differential Revision: https://reviews.llvm.org/D107065