pgsql: Fix typos and incorrect type in read_stream.c

Fix typos and incorrect type in read_stream.c

max_ios should be int rather than int16, otherwise there's not much
point in doing:

max_ios = Min(max_ios, PG_INT16_MAX);

Discussion: https://postgr.es/m/CAApHDvr9Un-XpDr_+AFdOGM38O2K8SpfoHimqZ838gguTGYBiQ@mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/2ea4b29277222efe59dc25ed8385c8bcb1a3ed0f

Modified Files
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src/backend/storage/aio/read_stream.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)