southbridge/amd/pi/avalon/pci_devs.h: Correct define `EHCI3_DEV`

It appears the decimal value was used instead of the hexadecimal value.

Apply commit 59919ad1 (southbridge/amd/agesa/hudson: Correct incorrect
 #define) to AMD Avalon, whose `pci_devs.h` was copied from AMD Hudson.

The incorrect define was introduced in commit 2093c4f7 (AMD/agesa: Add
functions for AMD PCI IRQ routing).

Change-Id: I7ccc060e8fa032080375259c3b11d39e2deb8e9e
Signed-off-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-on: http://review.coreboot.org/7800
Tested-by: build bot (Jenkins)
Reviewed-by: Bruce Griffith <Bruce.Griffith@se-eng.com>