ata: sata_rcar: Remove unused variable in sata_rcar_init_controller()

drivers/ata/sata_rcar.c: In function 'sata_rcar_init_controller':
drivers/ata/sata_rcar.c:821:8: warning: unused variable 'base' [-Wunused-variable]

Fixes: da77d76b ("sata_rcar: Reset SATA PHY when Salvator-X board resumes")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Tejun Heo <tj@kernel.org>