device/pci_early.c: Mixes up variants of a typedefs to 'u32'

Unfortunately coreboot has to deal with ROMCC's short comings which has
lead to a little bit of confusion due to typedefs. Essentially, coreboot
defines four typedefs:

 * 'typedef struct device * device_t' in ramstage not in SIMPLE_DEVICE mode
 * 'typedef u32 device_t' in romstage or when SIMPLE_DEVICE is defined
 * 'typedef u32 pnp_devfn_t'
 * 'typedef u32 pci_devfn_t'

Some early functions make use of 'device_t' over 'pci_devfn_t' and since
the C type-checker does not enforce typedefs to the same type 'u32'
these are never noticed. Fix these so that 'device_t' does not conflict
in romstage for later work. We later plan to have 'pnp_devfn_t' and
'pci_devfn_t' as the only variants of 'u32' and 'device_t' to be a
struct pointer type exclusively.

Change-Id: I948801f5be968a934798f1bad7722649758cd4d3
Signed-off-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>
Reviewed-on: http://review.coreboot.org/6225
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <patrick@georgi-clan.de>