pcmcia: honor saved flags in yenta_socket's I365_CSCINT register

Instead of overwriting the I365_CSCINT register, save the old value and
merely change the bits we care about.

Part 1 of a series to allow the ISA irq to be used for Cardbus devices
if the socket's PCI irq is unusable.

[linux@dominikbrodowski.net: split up the original patch, commit message]

Signed-off-by: Jens Kuenzer <Jens.Kuenzer@fpga.homeip.net>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
diff --git a/drivers/pcmcia/i82365.h b/drivers/pcmcia/i82365.h
index 849ef1b..3f84d7a 100644
--- a/drivers/pcmcia/i82365.h
+++ b/drivers/pcmcia/i82365.h
@@ -95,6 +95,7 @@
 #define I365_CSC_DETECT	0x08
 #define I365_CSC_ANY	0x0F
 #define I365_CSC_GPI	0x10
+#define I365_CSC_IRQ_MASK	0xF0
 
 /* Flags for I365_ADDRWIN */
 #define I365_ENA_IO(map)	(0x40 << (map))