EDAC/versal: Read num_csrows and num_chans using the correct bitfield macro

Fix the extraction of num_csrows and num_chans. The extraction of the
num_rows is wrong. Instead of extracting using the FIELD_GET it is
calling FIELD_PREP.

The issue was masked as the default design has the rows as 0.

Fixes: 6f15b178 ("EDAC/versal: Add a Xilinx Versal memory controller driver")
Closes: https://lore.kernel.org/all/60ca157e-6eff-d12c-9dc0-8aeab125edda@linux-m68k.org/Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Shubhrajyoti Datta <shubhrajyoti.datta@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20231215053352.8740-1-shubhrajyoti.datta@amd.com

drivers/edac/versal_edac.c

@@ -966,10 +966,10 @@ static int mc_probe(struct platform_device *pdev)
 	edac_mc_id = emif_get_id(pdev->dev.of_node);
 
 	regval = readl(ddrmc_baseaddr + XDDR_REG_CONFIG0_OFFSET);
-	num_chans = FIELD_PREP(XDDR_REG_CONFIG0_NUM_CHANS_MASK, regval);
+	num_chans = FIELD_GET(XDDR_REG_CONFIG0_NUM_CHANS_MASK, regval);
 	num_chans++;
 
-	num_csrows = FIELD_PREP(XDDR_REG_CONFIG0_NUM_RANKS_MASK, regval);
+	num_csrows = FIELD_GET(XDDR_REG_CONFIG0_NUM_RANKS_MASK, regval);
 	num_csrows *= 2;
 	if (!num_csrows)
 		num_csrows = 1;