Merge linker scripts in bootrom to have a single linker script for the bootloader proper (previously known as bootrom-merged.s19)

Remove the now unnecessary files (merge-srec.pl, ldscript-ram-jtag)
Note that this drops the dependency on perl for bootrom build, so end-users who don't touch the FPGA bitstream will not need perl anymore

tools/merge-srec.pl

@@ -1,23 +0,0 @@
-# merge the code that initially executes out of flash with the RAM image
-
-($flashFile, $ramFile) = @ARGV;
-
-open(FLASH, $flashFile) or die "$flashFile: $!\n";
-
-while(<FLASH>) {
-	print if /^S3/;
-	$EOF_record = $_ if /^S[789]/;
-}
-
-open(RAM, $ramFile) or die "$ramFile: $!\n";
-
-while(<RAM>) {
-	if(/^S3(..)(........)(.*)([0-9a-fA-F]{2})/) {
-		$addr = sprintf('%08X', hex($2) - 0x00200000 + 0x200);
-		$line = "$1$addr$3";
-		$checksum = 0;
-		$checksum += $_ foreach map(hex, unpack("a2"x40, $line));
-		print "S3$line", sprintf("%02X", ($checksum%256)^0xff ), "\n";
-	}
-}
-print $EOF_record;