Fix PDK dupbuild issues

The PDK uses pattern rules in order to install files from the PDK. When
those files already have build rules, the explicit rules override the
pattern rules, and everything works. But because Make (and Kati) doesn't
attempt to clean the file paths, if one of the rules has a redundant /,
we'll export two ninja rules, and ninja will error out with a dupbuild
error.

The PDK pattern rules are clean, but the explicit notice file creation
was not, it was always adding a double // in between NOTICE_FILES/src
and the module path.

Some modules were also setting a LOCAL_MODULE_PATH with a trailing /,
which is redundant, and also hits the above problem. Instead of fixing
all of the modules, just strip a trailing / from my_module_path.

Bug: 33451638
Test: Build with a PDK
Change-Id: Iff3e98fd191ea90626b9b89f179537e8a75f5ef2