[Docs][llvm-mc] Fix location of statement

The comment moved is referring to the --output-asm-syntax flag rather
than the --print-imm-hex flag, but seems to have mistakenly been put
under the definition of that flag due to some misplaced line numbers on
phabricator.

GitOrigin-RevId: 8f7496b0b106c7e348b87562128073889a6a41df
1 file changed