kvm-unit-test: fix incorrect script output

./run_tests.sh
)ASS apic-split (50 tests;
)ASS ioapic-split (19 tests;
)ASS apic (50 tests;
)ASS ioapic (19 tests;
)ASS smptest (1 tests;
)ASS smptest3 (1 tests;

The problem come from commit 0f4f2acb
(x86: io: force carriage return on \n put to serial port). It maybe output
well in real hardware, but it let outputs to file with '\r'.

Signed-off-by: Peng Hao <peng.hao2@zte.com.cn>