erofs: kill prio and nofail of erofs_get_meta_page()

erofs: kill prio and nofail of erofs_get_meta_page()

As Christoph pointed out [1],
"Why is there __erofs_get_meta_page with the two weird
booleans instead of a single erofs_get_meta_page that
gets and gfp_t for additional flags and an unsigned int
for additional bio op flags."

And since all callers can handle errors, let's kill
prio and nofail and erofs_get_inline_page() now.

[1] https://lore.kernel.org/r/20190830162812[email protected]/
Reported-by: Christoph Hellwig <[email protected]>
Signed-off-by: Gao Xiang <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>