ext4: remove useless resetting io_end_size in mpage_process_page()

The command "make clang-analyzer" detects dead stores in
mpage_process_page() function.

Do not reset io_end_size to 0 in the current paths, as the function
exits on those paths without further using io_end_size.

Signed-off-by: Nghia Le <nghialm78@gmail.com>
Link: https://lore.kernel.org/r/20211025221803.3326-1-nghialm78@gmail.com


Signed-off-by: Theodore Ts'o <tytso@mit.edu>