openpower-dumps: eliminate special generated config file

Meson calls for 'clang-tidy' changed behavior such that it will call
for all "c-like" files in a repository rather than just the ones pulled
in as dependencies.  When openpower extensions are disabled, this means
that we fail clang-tidy because required header files do not exist.

The generated header file has a few constants that are not openpower
specific.  Move them to the top-level config.h.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I2ee5c9246b9c47b564130c22ff8e02fee7f752b1