ARM: mvebu: Warn about memory chunks too small for DDR training

For each memory region the first 10K are reserved for DDR training. Emit
a warning if the area happens to be smaller than these 10K. This should
not happen, but if it does this message simplifies diagnosing the
problem.

This fixes a W=1 compiler error:

	arch/arm/mach-mvebu/board-v7.c: In function ‘mvebu_scan_mem’:
	arch/arm/mach-mvebu/board-v7.c:84:27: error: variable ‘size’ set but not used [-Werror=unused-but-set-variable]
	   84 |                 u64 base, size;
	      |                           ^~~~
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Gregory CLEMENT <gregory.clement@bootlin.com>

arch/arm/mach-mvebu/board-v7.c

@@ -86,6 +86,9 @@ static int __init mvebu_scan_mem(unsigned long node, const char *uname,
 		base = dt_mem_next_cell(dt_root_addr_cells, &reg);
 		size = dt_mem_next_cell(dt_root_size_cells, &reg);
 
+		if (size < MVEBU_DDR_TRAINING_AREA_SZ)
+			pr_warn("Too little memory to reserve for DDR training\n");
+
 		memblock_reserve(base, MVEBU_DDR_TRAINING_AREA_SZ);
 	}