With this patch, we can generate simple immediate-shift instructions for
immediates outside the range "0 <= imm < width". Several related
instruction selectors have also been updated accordingly.

Example of generated code:

    ---- Before ---         ---- After ----
    movz w0, #33            lsr w0, w1, #1
    lsr  w0, w1, w0

BUG=

Review URL: https://codereview.chromium.org/1179893003

Cr-Commit-Position: refs/heads/master@{#28977}