Currently we are dropping the end of the device path in the ekl when it
contains `|' characters, as in sample.elk for example. Rework the ekl
parsing to fix this.

  Before: `Acpi(PNP0A08,0)/Pci(0'
   After: `Acpi(PNP0A08,0)/Pci(0|0)/Pci(0|0)'

Signed-off-by: Vincent Stehlé <vincent.stehle@arm.com>