erofs: tidy up redundant includes

- Remove unused includes like <linux/parser.h> and <linux/prefetch.h>;

- Move common includes into "internal.h".

Signed-off-by: Ferry Meng <mengferry@linux.alibaba.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: Yue Hu <huyue2@coolpad.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Link: https://lore.kernel.org/r/20231026021627.23284-2-mengferry@linux.alibaba.com


Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>