pgsql: Fix some comments of do_pg_backup_start() and do_pg_backup_stop(

Fix some comments of do_pg_backup_start() and do_pg_backup_stop()

Both functions referred to an incorrect variable name, so make the whole
more consistent.

Oversight in 7d70809.

Author: Kyotaro Horiguchi, Bharath Rupireddy
Discussion: https://postgr.es/m/20220927.172427.467118514018439476.horikyota.ntt@gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/2e560b974ec7f7e8fe47e765e7c276422015ff3b

Modified Files
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src/backend/access/transam/xlog.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)