Changed the isapnp semaphore to a mutex.

[akpm@linux-foundation.org: no externs-in-c]
[akpm@linux-foundation.org: build fix]
Signed-off-by: Daniel Walker <dwalker@mvista.com>
Cc: Bjorn Helgaas <bjorn.helgaas@hp.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>