ARM: 8047/1: rwsem: use asm-generic rwsem implementation

asm-generic offers an atomic-add based rwsem implementation, which
can avoid the need for heavier, spinlock-based synchronisation on the
fast path.

This patch makes use of the optimised implementation for ARM CPUs.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/Kconfig

@@ -165,12 +165,9 @@ config TRACE_IRQFLAGS_SUPPORT
 	bool
 	default y
 
-config RWSEM_GENERIC_SPINLOCK
-	bool
-	default y
-
 config RWSEM_XCHGADD_ALGORITHM
 	bool
+	default y
 
 config ARCH_HAS_ILOG2_U32
 	bool

arch/arm/include/asm/Kbuild

@@ -21,6 +21,7 @@ generic-y += parport.h
 generic-y += poll.h
 generic-y += preempt.h
 generic-y += resource.h
+generic-y += rwsem.h
 generic-y += sections.h
 generic-y += segment.h
 generic-y += sembuf.h