[Bluetooth] Let BT_HIDP depend on INPUT

This patch lets BT_HIDP depend on instead of select INPUT. This fixes
the following warning during an s390 build:

net/bluetooth/hidp/Kconfig:4:warning: 'select' used by config symbol
'BT_HIDP' refer to undefined symbol 'INPUT'

A dependency on INPUT also implies !S390 (and therefore makes the
explicit dependency obsolete) since INPUT is not available on s390.

The practical difference should be nearly zero, since INPUT is always
set to y unless EMBEDDED=y (or S390=y).
Signed-off-by: Adrian Bunk <bunk@stusta.de>

net/bluetooth/hidp/Kconfig

 config BT_HIDP
 	tristate "HIDP protocol support"
-	depends on BT && BT_L2CAP && (BROKEN || !S390)
-	select INPUT
+	depends on BT && BT_L2CAP && INPUT
 	help
 	  HIDP (Human Interface Device Protocol) is a transport layer
 	  for HID reports.  HIDP is required for the Bluetooth Human