Update Linux to v5.10.109

Sourced from [1]

[1] https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.10.109.tar.xz

Change-Id: I19bca9fc6762d4e63bcf3e4cba88bbe560d9c76c
Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
diff --git a/arch/powerpc/include/asm/dma.h b/arch/powerpc/include/asm/dma.h
index 1b4f025..6161a95 100644
--- a/arch/powerpc/include/asm/dma.h
+++ b/arch/powerpc/include/asm/dma.h
@@ -151,10 +151,9 @@
 #define DMA2_EXT_REG		0x4D6
 
 #ifndef __powerpc64__
-    /* in arch/ppc/kernel/setup.c -- Cort */
+    /* in arch/powerpc/kernel/setup_32.c -- Cort */
     extern unsigned int DMA_MODE_WRITE;
     extern unsigned int DMA_MODE_READ;
-    extern unsigned long ISA_DMA_THRESHOLD;
 #else
     #define DMA_MODE_READ	0x44	/* I/O to memory, no autoinit, increment, single mode */
     #define DMA_MODE_WRITE	0x48	/* memory to I/O, no autoinit, increment, single mode */