ARM: 8974/1: use SPARSMEM_STATIC when SPARSEMEM is enabled

The commit 3e347261 ("[PATCH] sparsemem extreme implementation")
made SPARSMEM_EXTREME the default option for configurations that enable
SPARSEMEM.

For ARM systems with handful of memory banks SPARSEMEM_EXTREME is an
overkill.

Ensure that SPARSMEM_STATIC is enabled in the configurations that use
SPARSEMEM.

Fixes: 3e347261 ("[PATCH] sparsemem extreme implementation")
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>