kernel.bbclass: Allow modules*.tar.gz generation to be inhibited

kernel.bbclass: Allow modules*.tar.gz generation to be inhibited

The modules.tar.gz archive is sometimes of no value and it can take
a noticeable time to build if many modules were enabled in the kernel
configuration.  The extraneous file also contributes to deploy/ clutter
and is a waste of disk space.

Allow it to be suppressed by setting MODULE_TARBALL_DEPLOY="0".

(From OE-Core rev: 262bfde1c5c51cc902b50bf0dda543434f12010c)

Signed-off-by: Phil Blundell <pb@pbcl.net>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
Signed-off-by: Saul Wold <sgw@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>