ldlinux: parse_kernel_type() parameter should be const

ldlinux: parse_kernel_type() parameter should be const

Since we always pass a const char * to parse_kernel_type(), change the
type of the parameter accordingly to get rid of the following
warnings,

ldlinux.c:66:3: warning: passing argument 1 of ‘parse_kernel_type’ discards qual
ifiers from pointer target type
ldlinux.c:14:25: note: expected ‘char *’ but argument is of type ‘const char *’
ldlinux.c:80:2: warning: passing argument 1 of ‘parse_kernel_type’ discards qual
ifiers from pointer target type
ldlinux.c:14:25: note: expected ‘char *’ but argument is of type ‘const char *’
ldlinux.c: In function ‘main’:

Signed-off-by: Matt Fleming <matt.fleming@intel.com>