Use bleeding-edge svd2rust

A pair of changes (rust-embedded/svd#119, rust-embedded/svd2rust#444)
recently went into the `svd2rust` and `svd-parser` crates. Until these
changes are part of a release have `update.sh` pull a fork of `svd2rust`
that uses the master version of `svd-parser`.

Author: gkelly

update.sh

@@ -5,7 +5,7 @@ set -xe
 
 # INSTALL DEPENDENCIES
 
-cargo install --force --version 0.17.0 svd2rust
+cargo install --force --git https://github.com/gkelly/svd2rust --branch bleeding-edge svd2rust
 cargo install --force --version 0.7.0 form
 
 python -m pip install -r requirements.txt