install: Remove jump label in really_install_package

Commit acfc0346 ("sr: Add performance control") added a jump label
with the purpose of disabling performance mode before exiting the function.

That jump label now collides with a variable initialization from a
recent ASB commit (since jumping over a variable initialization
using jump labels is not allowed).

Instead, do what the 14.1 version of the commit did, and disable
performance mode manually on the two occasions where that is needed.

Change-Id: I5a55256f15895f673ec093da5d9a9f99875b70d8