rust-target-config: Fix TARGET_C_INT_WIDTH with correct size

rust-target-config: Fix TARGET_C_INT_WIDTH with correct size

[YOCTO #15600]

The TARGET_C_INT_WIDTH value was incorrectly set to 64 instead of 32.
It is updated for PPC, Mips, and riscv64 architectures.

Discussion links for solution:
 https://lists.openembedded.org/g/openembedded-core/message/207486
 https://lists.openembedded.org/g/openembedded-core/message/207496

Signed-off-by: Harish Sadineni <Harish.Sadineni@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>