lib/Kconfig: remove DEBUG_PER_CPU_MAPS dependency for CPUMASK_OFFSTACK

Forcing CPUMASK_OFFSTACK to be conditoned on DEBUG_PER_CPU_MAPS doesn't
make a lot of sense nowaday. Even the original patch dating back to 2008,
aab46da ("cpumask: Add CONFIG_CPUMASK_OFFSTACK") didn't give any
rationale for such dependency.

Nowhere in the code supports the presumption that DEBUG_PER_CPU_MAPS is
necessary for CONFIG_CPUMASK_OFFSTACK. Make no mistake, it's good to
have DEBUG_PER_CPU_MAPS for debugging purpose or precaution, but it's
simply not a hard requirement for CPUMASK_OFFSTACK. Moreover, x86 Kconfig
already can set CPUMASK_OFFSTACK=y without DEBUG_PER_CPU_MAPS=y.
There is no reason other architectures cannot given the fact that they
have even fewer, if any, arch-specific CONFIG_DEBUG_PER_CPU_MAPS code than
x86.

Signed-off-by: Libo Chen <libo.chen@oracle.com>

lib/Kconfig

@@ -511,7 +511,7 @@ config CHECK_SIGNATURE
 	bool
 
 config CPUMASK_OFFSTACK
-	bool "Force CPU masks off stack" if DEBUG_PER_CPU_MAPS
+	bool "Force CPU masks off stack"
 	help
 	  Use dynamic allocation for cpumask_var_t, instead of putting
 	  them on the stack.  This is a bit more expensive, but avoids