sdk-var: linux-imx: Update to latest

Include the following commits:

varigit/linux-imx@b1bff6c46675 arm64: imx8_var_defconfig: build internal RTC driver as module
varigit/linux-imx@f283cad3c0c6 gpio: pca953x: Introduce standard-regs-fallback property
varigit/linux-imx@6139f6559734 arm64: dts: imx95-var-dart: Enable NETC PTP timer
varigit/linux-imx@1a01dbb8b45e imx95-var-dart: Enable pull-up on ENET1_RGMII_RD3 for MXL MDIO strap

Signed-off-by: Diego Dorta <diego.d@variscite.com>

Author: dorta

configs/sdk-var.yml

@@ -167,7 +167,7 @@ repo:
 # kernel and modules git repositories
   linux:
     url:  https://github.com/varigit/linux-imx.git
-    commit: 0f9ef1c304488b498f5bf5e1fdb66ab6a028667e
+    commit: b1bff6c466755d4ffd904eaa5876952eba566161
 
   cryptodev_linux:
     url:  https://github.com/cryptodev-linux/cryptodev-linux.git