bio-integrity: remove EXPORT_SYMBOL for bio_integrity_init_slab()
I got section mismatch message about bio_integrity_init_slab().
WARNING: fs/built-in.o(__ksymtab+0xb60): Section mismatch in reference from the variable __ksymtab_bio_integrity_init_slab to the function .init.text:bio_integrity_init_slab()
The symbol bio_integrity_init_slab is exported and annotated __init Fix
this by removing the __init annotation of bio_integrity_init_slab or drop
the export.
It only call from init_bio(). The EXPORT_SYMBOL() can be removed.