logread: don't call shmdt() before exit, kernel does it for us.

function                                             old     new   delta
logread_main                                         472     466      -6
interrupted                                           20       9     -11
error_exit                                            20       -     -20
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(add/remove: 0/1 grow/shrink: 0/2 up/down: 0/-37)             Total: -37 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
1 file changed