tesseract-ocr: fix typo in variable name

TESSERACT_OCF_CONF_OPTS
            ^

Found using [1]:
check-package --include-only TypoInPackageVariable $(find * -type f)
and manually fixed.

[1] http://patchwork.ozlabs.org/patch/729672/

Signed-off-by: Ricardo Martincoski <ricardo.martincoski@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/tesseract-ocr/tesseract-ocr.mk

@@ -20,7 +20,7 @@ TESSERACT_OCR_DEPENDENCIES = leptonica host-pkgconf
 TESSERACT_OCR_INSTALL_STAGING = YES
 TESSERACT_OCR_CONF_ENV = \
 	LIBLEPT_HEADERSDIR=$(STAGING_DIR)/usr/include/leptonica
-TESSERACT_OCF_CONF_OPTS = \
+TESSERACT_OCR_CONF_OPTS = \
 	--disable-opencl
 
 # Language data files download