Config.in.legacy: fix typo

Fix typo added by commit 7527324132878f98999539bdd97bd3518747f585:
brcmfmac-sdio-firmware-rpi by brcmfmac_sdio-firmware-rpi

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

Config.in.legacy

@@ -154,7 +154,7 @@ config BR2_PACKAGE_RPI_BT_FIRMWARE
 	select BR2_PACKAGE_BRCMFMAC_SDIO_FIRMWARE_RPI_BT
 	help
 	  Package rpi-bt-firmware was moved as option to
-	  package brcmfmac-sdio-firmware-rpi.
+	  package brcmfmac_sdio-firmware-rpi.
 
 config BR2_PACKAGE_RPI_WIFI_FIRMWARE
 	bool "rpi-wifi-firmware package was renamed"
@@ -164,7 +164,7 @@ config BR2_PACKAGE_RPI_WIFI_FIRMWARE
 	select BR2_PACKAGE_BRCMFMAC_SDIO_FIRMWARE_RPI_WIFI
 	help
 	  Package rpi-wifi-firmware was moved as option to
-	  package brcmfmac-sdio-firmware-rpi.
+	  package brcmfmac_sdio-firmware-rpi.
 
 config BR2_PACKAGE_HOST_GDB_PYTHON
 	bool "GDB Python2 support removed"