Read virtual switch current values correctly
Read virtual switch current values correctly

As dev switch and recovery switch may be virtual, crossystem has to
distinguish virtual switches from physical ones.

Since to a virtual switch, its current value should always equal to its
boot value, return a boot value when asked for a current value.

Signed-off-by: Che-Liang Chiou <57969107b634cf11cb64e9d768fd46929066adab@chromium.org>

BUG=chrome-os-partner:10007
TEST=crossystem devsw_cur|recoverysw_cur show correct value on Snow

Change-Id: Ia73147ecd5528a3cc5276aff02a632ce4f52ea8b
Reviewed-on: https://gerrit.chromium.org/gerrit/26568
Commit-Ready: Che-Liang Chiou <57969107b634cf11cb64e9d768fd46929066adab@chromium.org>
Tested-by: Che-Liang Chiou <57969107b634cf11cb64e9d768fd46929066adab@chromium.org>
Reviewed-by: Tom Wai-Hong Tam <04b587fdf5845741a0c5a8b9cd59ca72d73ef8fc@chromium.org>

ccaapton/vboot_reference,geekboxzone/mmallow_external_vboot_reference,geekboxzone/mmallow_external_vboot_reference,coreboot/vboot,geekboxzone/mmallow_external_vboot_reference,coreboot/vboot,marineam/seismograph,acorn-marvell/vboot_reference,acorn-marvell/vboot_reference,ccaapton/vboot_reference,ccaapton/vboot_reference,acorn-marvell/vboot_reference,ionave/seismograph,coreboot/vboot,coreboot/vboot,ccaapton/vboot_reference,ionave/seismograph,acorn-marvell/vboot_reference,geekboxzone/mmallow_external_vboot_reference,marineam/seismograph,geekboxzone/mmallow_external_vboot_reference,marineam/seismograph,ionave/seismograph,marineam/seismograph,coreboot/vboot