[Buildroot] [git commit branch/2020.02.x] package/gcc: fix download url when using upstream gcc for csky

commit: https://git.buildroot.net/buildroot/commit/?id=2d6dc56cd947d553ce9a4ec2f52682ddfc84166e
branch: https://git.buildroot.net/buildroot/commit/?id=refs/heads/2020.02.x

When the csky cpu support was added [1], the gcc download url was selected
depending on the csky cpu architecture (BR2_csky) rather than the csky gcc
fork version (BR2_GCC_VERSION_CSKY)[2].

When adding gcc 9.x version [3], we forgot to update the condition in order
to use the url to the gcc csky fork only when BR2_GCC_VERSION_CSKY=y.

Due to this error, the toolchain build with the upstream gcc 9.x for csky
cpu is broken due a download error.

Fix this by using BR2_GCC_VERSION_CSKY instead of BR2_csky.

Fixes:
https://gitlab.com/kubu93/buildroot/-/jobs/470072924

[1] 7873a5bd5ebbeb1674293dae6b06b50f0a1f2184
[2] https://git.buildroot.net/buildroot/tree/package/gcc/gcc.mk?id=7873a5bd5ebbeb1674293dae6b06b50f0a1f2184#n19
[3] 089000eccf584d611ad1a8e5400436952450e883

Signed-off-by: Romain Naour <redacted>
Cc: Yann E. MORIN <redacted>
Cc: Guo Ren <guoren@kernel.org>
Cc: Arnout Vandecappelle <redacted>
Cc: Peter Korsgaard <peter@korsgaard.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
(cherry picked from commit a85b464b9440ae97dabb961086d9285947c7b283)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
---
 package/gcc/gcc.mk | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/package/gcc/gcc.mk b/package/gcc/gcc.mk
index 128293570d..524ca83db0 100644
--- a/package/gcc/gcc.mk
+++ b/package/gcc/gcc.mk

@@ -13,7 +13,7 @@ GCC_VERSION = $(call qstrip,$(BR2_GCC_VERSION))
 ifeq ($(BR2_GCC_VERSION_ARC),y)
 GCC_SITE = $(call github,foss-for-synopsys-dwc-arc-processors,gcc,$(GCC_VERSION))
 GCC_SOURCE = gcc-$(GCC_VERSION).tar.gz
-else ifeq ($(BR2_csky),y)
+else ifeq ($(BR2_GCC_VERSION_CSKY),y)
 GCC_SITE = $(call github,c-sky,gcc,$(GCC_VERSION))
 GCC_SOURCE = gcc-$(GCC_VERSION).tar.gz
 else