[AGPGART] fix compile errors

This fixes the following compile failures of agpgart drivers.
These errors were inserted by the recent AGPGART constification patch.

drivers/char/agp/uninorth-agp.c:492: error: expected '{' before 'const'
drivers/char/agp/uninorth-agp.c:517: error: expected '{' before 'const'
drivers/char/agp/uninorth-agp.c: In function 'agp_uninorth_probe':
drivers/char/agp/uninorth-agp.c:634: error: 'u3_agp_driver' undeclared (first use in this function)
drivers/char/agp/uninorth-agp.c:634: error: (Each undeclared identifier is reported only once
drivers/char/agp/uninorth-agp.c:634: error: for each function it appears in.)
drivers/char/agp/uninorth-agp.c:636: error: 'uninorth_agp_driver' undeclared (first use in this function)

Signed-off-by: Ryusuke Konishi <ryusuke@osrg.net>
Signed-off-by: Dave Jones <davej@redhat.com>