[SCSI] ufs: Separate PCI code into glue driver

This patch separates PCI code from ufshcd.c and makes it as a
core driver module and adds a new file ufshcd-pci.c as PCI glue
driver.

[jejb: strip __devinit and devexit_p()]
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Namjae Jeon <linkinjeon@gmail.com>
Reviewed-by: Subhash Jadavani <subhashj@codeaurora.org>
Tested-by: Maya Erez <merez@codeaurora.org>
Signed-off-by: Vinayak Holikatti <vinholikatti@gmail.com>
Signed-off-by: Santosh Yaraganavi <santoshsy@gmail.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>