scsi: ufs: select CONFIG_NLS

A recent change to ufshcd introduced a call to utf16s_to_utf8s, a
function that is provided by the NLS module, so we get a link error when
that is not present:

drivers/scsi/built-in.o: In function `ufshcd_read_string_desc':
:(.text+0x124d0): undefined reference to `utf16s_to_utf8s'

This adds a Kconfig 'select' statement to avoid the build error.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Fixes: b573d484 ("scsi: ufs: add support to read device and string descriptors")
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>