bctoolbox: remove redundant mbedtls dependency

Fixes:

  Makefile:532: *** mbedtls is in the dependency chain of bctoolbox that
  has added it to its _DEPENDENCIES variable without selecting it or
  depending on it from Config.in.  Stop.

Signed-off-by: Peter Seiderer <ps.report@gmx.net>
Acked-by: Jörg Krause <joerg.krause@embedded.rocks>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/bctoolbox/bctoolbox.mk

@@ -8,7 +8,6 @@ BCTOOLBOX_VERSION = 0.4.0
 BCTOOLBOX_SITE = $(call github,BelledonneCommunications,bctoolbox,$(BCTOOLBOX_VERSION))
 BCTOOLBOX_LICENSE = GPLv2+
 BCTOOLBOX_LICENSE_FILES = COPYING
-BCTOOLBOX_DEPENDENCIES = mbedtls
 BCTOOLBOX_INSTALL_STAGING = YES
 
 # Set CMAKE_SKIP_RPATH to prevent bctoolbox from adding the rpath to