omap3: Fix booting if package is uninitialized

Otherwise bringing up new boards can be harder:

Unable to handle kernel NULL pointer dereference at virtual address 00000000
pgd = c0004000
[00000000] *pgd=00000000
Internal error: Oops: 5 [#1]
last sysfs file:
Modules linked in:
CPU: 0    Not tainted  (2.6.33-rc2-00015-g0bc9c93-dirty #37)
PC is at omap_mux_init+0xa4/0x3d8
LR is at omap_mux_init+0x3c/0x3d8
...

Signed-off-by: Tony Lindgren <tony@atomide.com>