swtpm: Fix compilation error on 32bit machines

Fix the following compilation error occurring on 32bit machines:

swtpm_nvstore_linear_file.c: In function 'SWTPM_NVRAM_LinearFile_Mmap':
swtpm_nvstore_linear_file.c:58:20: error: comparison of integer expressions of different signedness: '__off_t' {aka 'long int'} and 'unsigned int' [-Werror=sign-compare]
   58 |     if (st.st_size >= (uint32_t)sizeof(struct nvram_linear_hdr)) {
      |                    ^~

Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
1 file changed