IB: Remove reference to obsolete CONFIG_IPATH_CORE

Since commit b1c1b6a3

 ("IB/ipath: merge ipath_core and ib_ipath
drivers"), CONFIG_IPATH_CORE no longer exists, so there's no reason to
have a line for it in drivers/Makefile.

Pointed out by Robert P. J. Day <rpjday@mindspring.com>.
Signed-off-by: Roland Dreier <rolandd@cisco.com>

drivers/Makefile

@@ -72,7 +72,6 @@ obj-$(CONFIG_CPU_FREQ)		+= cpufreq/
 obj-$(CONFIG_MMC)		+= mmc/
 obj-$(CONFIG_NEW_LEDS)		+= leds/
 obj-$(CONFIG_INFINIBAND)	+= infiniband/
-obj-$(CONFIG_IPATH_CORE)	+= infiniband/
 obj-$(CONFIG_SGI_SN)		+= sn/
 obj-y				+= firmware/
 obj-$(CONFIG_CRYPTO)		+= crypto/