libata: remove unused functions

This patch removes the following obsolete functions:
- libata-core.c: __sata_phy_reset()
- libata-core.c: sata_phy_reset()
- libata-eh.c: ata_qc_timeout()
- libata-eh.c: ata_eng_timeout()

Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Tejun Heo <htejun@gmail.com>