ARM: 8719/1: NOMMU: work around maybe-uninitialized warning

The reworked MPU code produces a new warning in some configurations,
presumably starting with the code move after the compiler now makes
different inlining decisions:

arch/arm/mm/pmsa-v7.c: In function 'adjust_lowmem_bounds_mpu':
arch/arm/mm/pmsa-v7.c:310:5: error: 'specified_mem_size' may be used uninitialized in this function [-Werror=maybe-uninitialized]

This appears to be harmless, as we know that there is always at
least one memblock, and the only way this could get triggered is
if the for_each_memblock() loop was never entered.

I could not come up with a better workaround than initializing
the specified_mem_size to zero, but at least that is the value
that the variable would have in the hypothetical case of no
memblocks.

Fixes: 877ec119 ("ARM: 8706/1: NOMMU: Move out MPU setup in separate module")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Vladimir Murzin <vladimir.murzin@arm.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>