apm821xx: speed up ath9k-caldata extraction

Reading and writing to and from flash storage is slow and currently,
the ath10kcal_extract() scripts are even more at an disadvantage
because they use a block size of 1 to be able skip.

This patch reworks the extraction scripts to be much faster and
efficient by reading and writing the calibration data in possibly
one big block.

Signed-off-by: Christian Lamparter <chunkeey@gmail.com>

target/linux/apm821xx/base-files/etc/hotplug.d/firmware/10-ath9k-eeprom

@@ -20,7 +20,7 @@ ath9k_eeprom_extract() {
 	[ -n "$mtd" ] || \
 		ath9k_eeprom_die "no mtd device found for partition $part"
 
-	dd if=$mtd of=/lib/firmware/$FIRMWARE bs=1 skip=$offset count=$count 2>/dev/null || \
+	dd if=$mtd of=/lib/firmware/$FIRMWARE iflag=skip_bytes bs=$count skip=$offset count=1 2>/dev/null || \
 		ath9k_eeprom_die "failed to extract from $mtd"
 }
 
@@ -35,7 +35,7 @@ ath9k_ubi_eeprom_extract() {
 	[ -n "$ubi" ] || \
 		ath9k_eeprom_die "no UBI volume found for $part"
 
-	dd if=/dev/$ubi of=/lib/firmware/$FIRMWARE bs=1 skip=$offset count=$count 2>/dev/null || \
+	dd if=/dev/$ubi of=/lib/firmware/$FIRMWARE iflag=skip_bytes bs=$count skip=$offset count=1 2>/dev/null || \
 		ath9k_eeprom_die "failed to extract from $ubi"
 }