package/gcc-bare-metal: bump to version 15.2.0 to fix build

Since Buildroot commit [1] "package/gcc: bump 15.x series to 15.2.0",
gcc-bare-metal fails to download its sources. For example using the
commands:

	make zynqmp_kria_kv260_defconfig
	make source

fails with error:

	ERROR: No hash found for gcc-15.1.0.tar.xz

This is because the gcc-bare-metal package reuses the hash file and
the 15.x package patch directory from the gcc package (which was
bumped to 15.2.0), but still defines its _VERSION to 15.1.0.

This commit fixes this issue by bumping gcc-bare-metal to 15.2.0.

Fixes:
https://autobuild.buildroot.org/results/eda879fb8e1ccd696f01927087713b88a4b1a2c5
https://gitlab.com/buildroot.org/buildroot/-/jobs/11026775160

[1] b1dd235ad0

Cc: Ibai Erkiaga <ibai.erkiaga-elorza@amd.com>
Cc: Neal Frager <neal.frager@amd.com>
Cc: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Signed-off-by: Julien Olivain <ju.o@free.fr>
Acked-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Acked-by: Neal Frager <neal.frager@amd.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/gcc-bare-metal/15.1.0

@@ -1 +0,0 @@
-../gcc/15.1.0/

package/gcc-bare-metal/15.2.0

@@ -0,0 +1 @@
+../gcc/15.2.0

package/gcc-bare-metal/gcc-bare-metal.mk

@@ -4,7 +4,7 @@
 #
 ################################################################################
 
-GCC_BARE_METAL_VERSION = 15.1.0
+GCC_BARE_METAL_VERSION = 15.2.0
 GCC_BARE_METAL_SITE = $(BR2_GNU_MIRROR)/gcc/gcc-$(GCC_BARE_METAL_VERSION)
 GCC_BARE_METAL_SOURCE = gcc-$(GCC_BARE_METAL_VERSION).tar.xz