class/rootfs: Don't mess with recipe private RDEPENDS
class/rootfs: Don't mess with recipe private RDEPENDS

Add busybox to CLASS_RDEPENDS and not RDEPENDS, which should only be
modified by recipe code.

Signed-off-by: Esben Haabendal <c5ba3f1141bb30a64dd6c7e6726a53a85adc9442@prevas.dk>

sknsean/core,hundeboll/core,hundeboll/core,hundeboll/core,hundeboll/core,sknsean/core,diorcety/oe-lite-core,sknsean/core,sknsean/core,diorcety/oe-lite-core,sknsean/core