hammer: Do not define CONFIG_ROLLBACK_UPDATE for RW section
hammer: Do not define CONFIG_ROLLBACK_UPDATE for RW section

BRANCH=none
BUG=b:35586219
TEST=make newsizes saves ~420 bytes on hammer and staff.

Change-Id: I69a757cc8eb0545cfbb73df04ac36ea6e68ae933
Reviewed-on: https://chromium-review.googlesource.com/511984
Commit-Ready: Nicolas Boichat <f3daba1cdc403799935674d3cd4b0e5bd1804232@chromium.org>
Tested-by: Nicolas Boichat <f3daba1cdc403799935674d3cd4b0e5bd1804232@chromium.org>
Reviewed-by: Vincent Palatin <70a9964ec8fd10b0b08fcc8623c2add25ddf99ac@chromium.org>

coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec