soc: fsl: qe: drop broken lazy call of cpm_muram_init()

cpm_muram_alloc_common() tries to support a kind of lazy
initialization - if the muram_pool has not been created yet, it calls
cpm_muram_init(). Now, cpm_muram_alloc_common() is always called under

	spin_lock_irqsave(&cpm_muram_lock, flags);

and cpm_muram_init() does gen_pool_create() (which implies a
GFP_KERNEL allocation) and ioremap(), not to mention the fun that
ensues from cpm_muram_init() doing

	spin_lock_init(&cpm_muram_lock);

In other words, this has never worked, so nobody can have been relying
on it.

cpm_muram_init() is called from a subsys_initcall (either from
cpm_init() in arch/powerpc/sysdev/cpm_common.c or, via qe_reset(),
from qe_init() in drivers/soc/fsl/qe/qe.c).

Reviewed-by: Timur Tabi <timur@kernel.org>
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Li Yang <leoyang.li@nxp.com>