bsr: fix build problem with bsr_class static cleanup

In commit e55ce9fd

 ("bsr: make bsr_class a static const structure"),
the bsr_init function was converted to handle a static class structure,
but the conversion got a variable name wrong, which caused build errors
so fix that up.

Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Ivan Orlov <ivan.orlov0322@gmail.com>
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Link: https://lore.kernel.org/r/20230626142537.755ec782@canb.auug.org.au
Fixes: e55ce9fd

 ("bsr: make bsr_class a static const structure")
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>