Fix callout I2C path

In the 5.0 Linux kernel, an I2C device path segment changed:
    i2c@1e78a000 -> bus@1e78a000

Signed-off-by: Matt Spinler <spinler@us.ibm.com>
Change-Id: I6eec4ca9d570d7c6eceac0338c88967a78907b48
diff --git a/gen_callouts.pl b/gen_callouts.pl
index 5398aa5..5083557 100755
--- a/gen_callouts.pl
+++ b/gen_callouts.pl
@@ -36,7 +36,7 @@
 
 
 # paths
-my $i2cPath = "/sys/devices/platform/ahb/ahb:apb/ahb:apb:i2c\@1e78a000/1e78a100.i2c-bus/i2c-<port>/<port>-00<address>";
+my $i2cPath = "/sys/devices/platform/ahb/ahb:apb/ahb:apb:bus\@1e78a000/1e78a100.i2c-bus/i2c-<port>/<port>-00<address>";
 my $fsiMasterPath = "/sys/devices/platform/gpio-fsi/fsi0/slave\@00:00/raw";
 my $fsiSlavePath = "/sys/devices/platform/gpio-fsi/fsi0/slave\@00:00/00:00:00:0a/fsi1/slave\@<link>:00/raw";