Documentation: fix filesystems/locking.rst malformed table warnings

locking rules:

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ops			inode->i_lock	blocked_lock_lock	may block

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lm_notify:		yes		yes			no

lm_grant:		no		no			no

lm_break:		yes		no			no

lm_change		yes		no			no

lm_breaker_owns_lease:	no		no			no

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buffer_head

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locking rules:

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ops		mmap_lock	PageLocked(page)

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open:		yes

close:		yes

fault:		yes		can return with page locked

page_mkwrite:	yes		can return with page locked

pfn_mkwrite:	yes

access:		yes

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->fault() is called when a previously not present pte is about

to be faulted in. The filesystem must find and return the page associated