Revert "tslib: disable raw input plugin under kernel < v3.12"

This reverts commit 46d6aa520f2490928f27da716356b00da357cc99.

Since commit 7c60211ce382 (tslib: needs kernel headers 3.12)
BR2_TOOLCHAIN_HEADERS_AT_LEAST_3_12 is always enabled when building tslib. No
need to check for that.

Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/tslib/tslib.mk

@@ -14,8 +14,4 @@ TSLIB_AUTORECONF = YES
 TSLIB_INSTALL_STAGING = YES
 TSLIB_INSTALL_STAGING_OPTS = DESTDIR=$(STAGING_DIR) LDFLAGS=-L$(STAGING_DIR)/usr/lib install
 
-ifeq ($(BR2_TOOLCHAIN_HEADERS_AT_LEAST_3_12),)
-TSLIB_CONF_OPTS += --disable-input
-endif
-
 $(eval $(autotools-package))