quagga: fix BR2_PACKAGE_QUAGGA_TCP_ZEBRA

Since bump to version 0.99.21 and commit
b20c77321fa87f880ead2f27ecf19fd7c4f436da, BR2_PACKAGE_QUAGGA_TCP_ZEBRA
has been wrongly rename into BR2_PACKAGE_QUAGGA_TCP_ZERBRA

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/quagga/quagga.mk

@@ -45,7 +45,7 @@ QUAGGA_CONF_OPTS += $(if $(BR2_PACKAGE_QUAGGA_PIMD),--enable-pimd,--disable-pimd
 QUAGGA_CONF_OPTS += $(if $(BR2_PACKAGE_QUAGGA_WATCHQUAGGA),--enable-watchquagga,--disable-watchquagga)
 QUAGGA_CONF_OPTS += $(if $(BR2_PACKAGE_QUAGGA_ISISD),--enable-isisd,--disable-isisd)
 QUAGGA_CONF_OPTS += $(if $(BR2_PACKAGE_QUAGGA_BGP_ANNOUNCE),--enable-bgp-announce,--disable-bgp-announce)
-QUAGGA_CONF_OPTS += $(if $(BR2_PACKAGE_QUAGGA_TCP_ZERBRA),--enable-tcp-zebra,--disable-tcp-zebra)
+QUAGGA_CONF_OPTS += $(if $(BR2_PACKAGE_QUAGGA_TCP_ZEBRA),--enable-tcp-zebra,--disable-tcp-zebra)
 
 define QUAGGA_USERS
 	quagga -1 quagga -1 * - - - Quagga priv drop user