ACPI: EC: move acpi_ec_start() after acpi_ec_add()

This patch rearranges ec_install_handlers() and acpi_ec_start() so
acpi_ec_start() ends up just after acpi_ec_add().  A subsequent patch
will merge them.

Code movement only; no functional change.

Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
CC: Alexey Starikovskiy <astarikovskiy@suse.de>
Signed-off-by: Len Brown <len.brown@intel.com>